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Physics Practice Mid Term 1.1 Conceptual Questions ____ 1) How many significant figures are in the number 120.070? A) six B) five C) four D) three 1.2 Problems ____ 2) What is A) B) C) D) ____ expressed to the correct number of significant figures? 0.91 0.911 0.9108 0.9 3) The length and width of a rectangle are 1.125 m and 0.606 m, respectively. Multiplying, your calculator gives the product as 0.68175. Rounding properly to the correct number of significant figures, the area of the rectangle should be written as A) 0.68 m2 B) 0.682 m2 C) 0.6818 m2 D) 0.68175 m2 ____ 4) What is the sum of 2.67 + 1.976 + 2.1 expressed to the correct number of significant figures? A) 6.7 B) 6.75 C) 6.746 D) 6.7460 ____ 5) What is the result, expressed to the proper number of significant figures, of adding 23.4 to 91.237 and then subtracting 23.4? A) 91.237 B) 91.2 C) 91.3 D) 91.0 E) 91 ____ 6) A rectangular garden measures 15 m long and 13.70 m wide. What is the length of a diagonal from one corner of the garden to the other? A) 18 m B) 19 m C) 20 m D) 4.1 102 m ____ 7) A dog has three puppies. Spot weighs 12 ounces. Rascal weighs 9.5 ounces. Socks weighs 10.2 ounces. What is the total weight of the litter expressed to the correct number of significant figures? A) 31.7 ounces B) 31 ounces C) 32 ounces D) 30 ounces E) 31.70 ounces ____ 8) A traveler has about $536 in his checking account, about $2107 in his savings account and exactly $7.62 in his wallet. To the greatest precision warranted, how much money does this shopper have? A) $2651 B) $2,650 C) $2,650.6 D) $2,650.62 E) $2,650.620 ____ 9) Which of the following numbers is the smallest? A) 15 10-3 B) 0.15 100 3 C) 0.00015 10 D) 0.00000015 106 ____ 10) Write out the number 8.42 10-5 in full with a decimal point and correct number of zeros. A) 0.00000842 B) 0.0000842 C) 0.000842 D) 0.00842 ____ 11) Express the number 13.5 gigameters in meters without using scientific notation. A) 135,000 m B) 135,000,000 m C) 135,000,000,000 m D) 13,500,000,000 m ____ 12) How many nanoseconds does it take for a computer to perform one calculation if it performs calculations per second? A) 15 ns B) 67 ns C) 11 ns D) 65 ns ____ 13) The wavelength of the light from a certain laser is -9 this wavelength in nanometers? (1 nm = 10 m) A) 6.6 102 nm B) 6.6 103 nm C) 6.6 101 nm D) 6.6 104 nm where What is ____ 14) A speed of 60 mi/h is closest to which of the following? (2.54 cm = 1.00 in.) A) 60 m/s B) 20 m/s C) 30 km/h D) 120 m/s E) 30 m/s ____ 15) A person on a diet loses A) 2.6 103 g/s B) 1.6 105 g/s C) 44 g/s D) 6.4 104 g/s in a week. How many micrograms per second (g/s) are lost? ____ 16) A typical ruby-throated hummingbird is 8 cm long. Express its length in millimeters and micrometers (µm). A) 80 mm; 800 µm B) 80 mm; 80,000 µm C) 800 mm; 0.008 µm D) 800 mm; 0.8 µm E) 0.8 mm; 8000 µm ____ 17) A jogger has a mass of 50 kg. Express her mass in grams and micrograms (µg). A) 50,000 g; 5 106 µg B) 500,000 g; 500 106 µg C) 500,000 g; 5000 µg D) 50,000 g; 5 1010 µg E) 50,000 g; 50,000 µg ____ 18) A jar of peanut butter costs $3.29. Express its price in dekadollars and decidollars. A) 0.329 dekadollars; 0.329 decidollars B) 32.9 dekadollars; 0.329 decidollars C) 329 dekadollars; 32.9 decidollars D) 0.329 dekadollars; 32.9 decidollars E) 32.9 dekadollars; 329 decidollars ____ 19) The following conversion equivalents are given: 1.0 mile = 5280 ft 1.0 ft = 12 in 1 m = 39.37 in 1.0 hour = 60 min 1.0 min = 60 s If a deer runs at 4.7 mi/h, its speed, in meters per second, is closest to A) 2.1 m/s. B) 1.7 m/s. C) 1.9 m/s. D) 2.3 m/s. E) 2.5 m/s. ____ 20) A speed of 65 miles per hour is the same as which of the following? (1.00 ft = 30.48 cm) A) 24 m/s B) C) D) E) 29 m/s 32 m/s 37 m/s 42 m/s ____ 21) The following conversion equivalents are given: 1.0 kg = 1000 g 1.0 l = 1000 1.0 l = 0.0353 The density of a certain liquid is 0.83 g/ . The density of this liquid, expressed in kg/ft3, is closest to A) 24 kg/ft3. B) 19 kg/ft3. C) 21 kg/ft3. D) 26 kg/ft3. E) 28 kg/ft3. ____ 22) Your car gets 34.7 mi/gal on a vacation trip in the U.S. If you were figuring your mileage in Europe, how many km/L did it get? (3.79 L = 1.00 gal; 1.00 mi = 1.61 km) A) 14.7 km/L B) 9.16 km/L C) 55.9 km/L D) 32.4 km/L ____ 23) There are 640 acres in a square mile, and 5280 feet in 1.00 mile. What is the length in feet (to the nearest foot) of the side of a square having an area of 1.00 acre? A) 660 feet B) 209 feet C) 165 feet D) 412 feet E) 435 feet ____ 24) An American football field, including end zones, is 360 feet long and 160 feet wide. If you needed to describe it for someone in Europe using the metric system, which one of the following quantities would be closest to its area in square meters? (2.54 cm = 1.00 in.) A) 4,920 m2 B) 5,350 m2 C) 88.0 m2 D) 12,100 m2 E) 13,200 m2 ____ 25) Wall posters are usually sold curled up in cylindrical cardboard tubes. If the length of the tube is 84.5 cm, and the inside diameter of the tube is 2.40 cm, what is the area of the poster expressed to the correct number of significant figures? (Assume the poster is just as long as the tube and does not overlap itself.) A) 202.8 cm2 B) 637.1 cm2 C) 203 cm2 D) 319 cm2 E) 637 cm2 ____ 26) A spherical fruit has a radius of 3.23 cm. What is the volume of the fruit in cubic meters? A) 1.41 10-4 m3 B) 1.41 m3 C) 4.23 10-4 m3 D) 4.23 m3 ____ 27) The mass of Mars, 6.40 1023 kg, is about one-tenth that of Earth, and its radius, 3395 km, is about half that of Earth. What is the mean density (mass divided by volume) of Mars in kilograms per cubic meter? A) 9.76 102 kg/m3 B) 1.95 103 kg/m3 C) 3.90 103 kg/m3 D) 7.81 103 kg/m3 ____ 28) In Einstein's famous equation E = mc2, describing the relationship between matter and energy, E stands for energy, m stands for mass, and c is the speed of light in vacuum. What are the SI units of E? A) kg/s B) kg/s2 C) kg · m/s2 D) s2 / (kg · m) E) kg · m2 / s2 ____ 29) Estimate how many pennies would you have to stack to reach from the floor to an average 8-ft ceiling. A) 2 103 B) 2 102 C) 2 104 D) 2 105 E) 2 106 ____ 30) Which of the following is the most reasonable estimate of the number of characters (typed letters or numbers) in a 609-page book? Assume an average of 194 words per page and a reasonable average number of letters per word. A) 5 105 char B) 5 107 char C) 5 106 char D) 5 104 char ____ 31) A marathon race is 26 mi and 385 yd long. Estimate how many strides would be required to run a marathon. Assume a reasonable value for the average number of feet/stride. A) 4.5 104 strides B) 4.5 103 strides C) 4.5 105 strides D) 4.5 106 strides ____ 32) Estimate the number of times an average person's heart beats in a lifetime. Assume the average heart rate is and a life span of 75 years. A) 3 109 beats B) 3 108 beats C) 3 1010 beats D) 3 107 beats 2.1 Conceptual Questions ____ 33) Suppose that an object travels from one point in space to another. Make a comparison between the magnitude of the displacement and the distance traveled by this object. A) The displacement is either greater than or equal to the distance traveled. B) The displacement is always equal to the distance traveled. C) The displacement is either less than or equal to the distance traveled. D) The displacement can be either greater than, smaller than, or equal to the distance traveled. ____ 34) An object is moving with constant non-zero velocity in the +x direction. The velocity versus time graph of this object is A) a horizontal straight line. B) a vertical straight line. C) a straight line making an angle with the time axis. D) a parabolic curve. ____ 35) The motions of a car and a truck along a straight road are represented by the velocity-time graphs in the figure. The two vehicles are initially alongside each other at time t = 0. At time T, what is true of the distances traveled by the vehicles since time t = 0? A) They will have traveled the same distance. B) The truck will not have moved. C) The car will have travelled further than the truck. D) The truck will have travelled further than the car. ____ 36) Which of the following graphs represent an object at rest? (There could be more than one correct choice.) A) B) C) D) E) graph a graph b graph c graph d graph e 2.2 Problems 37) If, in the figure, you start from the Bakery, travel to the Cafe, and then to the Art Gallery (a) what distance you have traveled? (b) what is your displacement? ____ 38) An object moves 15.0 m north and then 11.0 m south. Find both the distance it has traveled and the magnitude of its displacement. A) 4.0 m, 26.0 m B) 26.0 m, 4.0 m C) 26.0 m, 26.0 m D) 4.0 m, 4.0 m 39) If you run a complete loop around an outdoor track of length 400 m in 100 s, find your (a) average velocity and (b) average speed. 40) If, in the figure, you start from the Bakery, travel to the Cafe, and then to the Art Gallery in 2.00 hours, what is your (a) average speed? (b) average velocity? 41) The graph in the figure shows the position of a particle as a function of time as it travels along the x- axis. (a) What is the average speed of the particle between t = 2.0 s and t = 4.0 s? (b) What is the average velocity of the particle between t = 2.0 s and t = 4.0 s? 42) The figure shows a graph of the position of a moving object as a function of time. What is the velocity of the object at each of the following times? (a) At t = 1.0 s (b) At t = 2.5 s (c) At t = 4.0 s (d) At t = 5.5 s 3.1 Conceptual Questions ____ 43) If the velocity of an object is zero at some point, then its acceleration must also be zero at that point. A) True B) False ____ 44) Which of the following situations is impossible? A) An object has velocity directed east and acceleration directed west. B) An object has velocity directed east and acceleration directed east. C) An object has zero velocity but non-zero acceleration. D) An object has constant non-zero acceleration and changing velocity. E) An object has constant non-zero velocity and changing acceleration. ____ 45) Suppose that a car traveling to the east (+x direction) begins to slow down as it approaches a traffic light. Which statement concerning its acceleration must be correct? A) Its acceleration is in the +x direction. B) Its acceleration is in the -x direction. C) Its acceleration is zero. D) Its acceleration is decreasing in magnitude as the car slows down. ____ 46) A racing car accelerates uniformly from rest along a straight track. This track has markers spaced at equal distances along it from the start, as shown in the figure. The car reaches a speed of 140 km/h as it passes marker 2. Where on the track was the car when it was traveling at half this speed, that is at 70 km/h? A) Before marker 1 B) At marker 1 C) Between marker 1 and marker 2 ____ 47) When a ball is thrown straight up with no air resistance, the acceleration at its highest point A) is upward B) is downward C) is zero D) reverses from upward to downward E) reverses from downward to upward ____ 48) The slope of a velocity versus time graph gives A) the distance traveled. B) velocity. C) acceleration. D) displacement. ____ 49) A child standing on a bridge throws a rock straight down. The rock leaves the child's hand at time t = 0 s. If we take upward as the positive direction, which of the graphs shown below best represents the acceleration of the stone as a function of time? A) D) B) E) C) 3.2 Problems ____ 50) An airplane increases its speed at the average rate of 15 m/s2. How much time does it take to increase its speed from 100 m/s to 160 m/s? A) 17 s B) 0.058 s C) 4.0 s D) 0.25 s 51) If a car accelerates at a uniform 4.0 m/s2, how long will it take to reach a speed of 80 km/hr, starting from rest? ____ 52) A cart starts from rest and accelerates uniformly at 4.0 m/s2 for 5.0 s. It next maintains the velocity it has reached for 10 s. Then it slows down at a steady rate of 2.0 m/s2 for 4.0 s. What is the final speed of the car? A) 20 m/s B) 16 m/s C) 12 m/s D) 10 m/s ____ 53) A cart with an initial velocity of 5.0 m/s to the right experiences a constant acceleration of 2.0 m/s2 to the right. What is the cart's displacement during the first 6.0 s of this motion? A) 10 m B) 55 m C) 66 m D) 80 m ____ 54) A car accelerates from accelerating? to at a constant rate of How far does it travel while A) B) C) D) 69 m 207 m 41 m 117 m ____ 55) A car is moving with a constant acceleration. At time t = 5.0 s its velocity is 8.0 m/s in the forward direction, and at time t = 8.0 s its velocity is 12.0 m/s forward. What is the distance traveled in that interval of time? A) 10 m B) 20 m C) 30 m D) 40 m E) 50 m ____ 56) A laser is thrown upward with a speed of 12 m/s on the surface of planet X where the acceleration due to gravity is 1.5 m/s2 and there is no atmosphere. What is the maximum height reached by the laser? A) 8.0 m B) 18 m C) 48 m D) 144 m ____ 57) An instrument is thrown upward with a speed of 15 m/s on the surface of planet X where the acceleration due to gravity is 2.5 m/s2 and there is no atmosphere. How long does it take for the instrument to return to where it was thrown? A) 6.0 s B) 8.0 s C) 10 s D) 12 s ____ 58) Human reaction time is usually greater than 0.10 s. If your friend holds a ruler between your fingers and releases it without warning, how far can you expect the ruler to fall before you catch it, assuming negligible air resistance? A) At least 3.0 cm B) At least 4.9 cm C) At least 6.8 cm D) At least 9.8 cm ____ 59) To determine the height of a bridge above the water, a person drops a stone and measures the time it takes for it to hit the water. If the height of the bridge is 41 m, how long will it take for the stone to hit the water? Neglect air resistance. A) 2.3 s B) 2.6 s C) 2.9 s D) 3.2 s E) 3.6 s 60) The figure shows a graph of the velocity of an object as a function of time. What is the acceleration of the object at the following times? (a) At 1.0 s (b) At 3.0 s 4.1 Conceptual Questions 61) A student adds two displacement vectors that have the magnitudes of 12.0 m and 5.0 m. What is the range of possible answers for the magnitude of the resultant vector? ____ 62) The sum of two vectors of fixed magnitudes has the greatest magnitude when the angle between these two vectors is A) 90° B) 180° C) 60° D) 0° E) 270° ____ 63) Consider two vectors A) B) C) D) and shown in the figure. The difference choice (a) choice (b) choice (c) choice (d) 64) Refer to the figure, which shows four vectors (a) Vector as expressed in terms of vectors A) + . B) - . C) - . (b) Vector as expressed in terms of vectors A) + . , , and , and . is given by and is given by - is best illustrated by B) C) - . . ____ 65) The eastward component of vector is equal to the westward component of vector and their northward components are equal. Which one of the following statements must be correct for these two vectors? A) Vector is parallel to vector B) Vector is antiparallel (in the opposite direction) to vector C) Vector must be perpendicular to vector D) The magnitude of vector E) The angle between vector . . . must be equal to the magnitude of vector and vector . must be 90°. ____ 66) For general projectile motion with no air resistance, the horizontal component of a projectile's velocity A) remains zero. B) remains a non-zero constant. C) continuously increases. D) continuously decreases. E) first decreases and then increases. ____ 67) For general projectile motion with no air resistance, the vertical component of a projectile's acceleration A) is always zero. B) remains a non-zero constant. C) continuously increases. D) continuously decreases. E) first decreases and then increases. ____ 68) In an air-free chamber, a pebble is thrown horizontally, and at the same instant a second pebble is dropped from the same height. Compare the times of fall of the two pebbles. A) The thrown pebble hits first. B) The dropped pebble hits first. C) They hit at the same time. D) We cannot tell without knowing which pebble is heavier. ____ 69) James and John dive from an overhang into the lake below. James simply drops straight down from the edge. John takes a running start and jumps with an initial horizontal velocity of 25 m/s. If there is no air resistance, when they reach the lake below A) the splashdown speed of James is larger than that of John. B) C) D) E) the splashdown speed of John is larger than that of James. they will both have the same splashdown speed. the splashdown speed of James must be 9.8 m/s larger than that of John. the splashdown speed of John must be 25 m/s larger than that of James. ____ 70) James and John dive from an overhang into the lake below. James simply drops straight down from the edge. John takes a running start and jumps with an initial horizontal velocity of 25 m/s. Compare the time it takes each to reach the lake below if there is no air resistance. A) James reaches the surface of the lake first. B) John reaches the surface of the lake first. C) James and John will reach the surface of the lake at the same time. D) Cannot be determined without knowing the mass of both James and John. E) Cannot be determined without knowing the weight of both James and John. 4.2 Problems ____ 71) When rolled down a mountainside at 7.0 m/s, the horizontal component of its velocity vector was 1.8 m/s. What was the angle of the mountain surface above the horizontal? A) 75° B) 57 ° C) 33° D) 15° ____ 72) When Jeff ran up a hill at 7.0 m/s, the horizontal component of his velocity vector was 5.1 m/s. What was the vertical component of Jeff's velocity? A) 4.8 m/s B) 4.3 m/s C) 3.8 m/s D) 3.4 m/s ____ 73) A player throws a football 50.0 m at 61.0° north of west. What is the westward component of the displacement of the football? A) 64.7m B) 55.0 m C) 0.00 m D) 74.0 m E) 24.2 m 74) A vector has components Ax = 12.0 m and Ay = 5.00 m. (a) What is the angle that vector makes with the +x-axis? (b) What is the magnitude of vector ? 75) The x and y components of a vector in a horizontal plane are 4.00 m and 3.00 m, respectively. (a) What is the magnitude of this vector? (b) What angle does this vector make with the positive +y-axis. to the north, then turn 60° to your right and walk another where you originally started? A) 68 m B) 39 m C) 75 m D) 35 m ____ 76) You walk How far are you from is 75 cm long and points at 30° above the +x-axis. Displacement vector 25 cm long and points along the -x-axis. Displacement vector is 40 cm long and points at 45° below the -x-axis. (a) Determine the x and y components of vector . (b) Determine the x and y components of vector . 77) Displacement vector (c) Determine the x and y components of vector . (d) Determine the x and y components of the resultant of these three vectors. (e) Determine the magnitude and direction of the resultant of these three vectors. ____ 78) Vector A) B) C) D) E) = 4.00 m points eastward and vector = 3.00 m points southward. The resultant vector + is given by 5.00 m at an angle of 36.9° south of east. 5.00 m at an angle of 53.1° south of east. 5.00 m at an angle of 71.6° south of east. 5.00 m at an angle of 18.4° south of east. 5.00 m at an angle of 26.6° south of east. ____ 79) The figure shows three vectors and their magnitudes and relative directions. The magnitude of the resultant of the three vectors is closest to A) B) C) D) E) 19 16 13 10 7.0 80) Two boys, Joe and Sam, who are searching for buried treasure start underneath the same tree. Joe walks 12 m east and then 12 m north, while Sam walks 15 m west and then 10 m south. Both boys then stop. Find the magnitude and direction of the vector from Sam to Joe. Express the direction of this vector by specifying the angle it makes with the west-to-east direction. 81) Two forces are acting on an object as shown in the figure. Assume that all the quantities shown are accurate to three significant figures. is (a) What is the magnitude of the resultant force on the object? (b) What is the direction of the resultant force? 82) The figure shows three vectors, , , and , having magnitudes 7.0 cm, 6.0 cm, and 4.0 cm, respectively. Find the x and y components of the resultant of these three vectors. 83) The figure shows four vectors, cm, and vectors and of these four vectors. , , , and . Vectors and each have a magnitude of 7.0 each have a magnitude of 4.0 cm. Find the x and y components of the sum 84) The figure shows four vectors, cm, and vectors and sum of these four vectors. , , , and . Vectors and both have a magnitude of 7.0 both have a magnitude of 4.0 cm. Find the magnitude and direction of the 85) The figure shows three vectors, , , and , along with their magnitudes. Determine the magnitude and direction of the vector given by + - . ____ 86) Three vectors, , , and , have the components shown in the table. What angle does the resultant of these three vectors make with the +x-axis? x component y component A) B) C) D) -3.5 m 4.5 m 0.00 m -6.5 m 5.5 m -2.5 m 24° above the +x-axis 24° below the +x-axis 66° above the +x-axis 66° below the +x-axis 87) A runner runs on a circular path of radius 10 m. What is the magnitude of the displacement of the jogger if he runs (a) half-way around the track? (b) all the way around the track? ____ 88) A ball is thrown with an initial velocity of 20 m/s at an angle of 60° above the horizontal. If we can neglect air resistance, what is the horizontal component of its instantaneous velocity at the exact top of its trajectory? A) 10 m/s B) 17 m/s C) 20 m/s D) zero ____ 89) A ball is thrown at an original speed of 8.0 m/s at an angle of 35° above the horizontal. If there is no air resistance, what is the speed of the ball when it returns to the same horizontal level? A) 4.0 m/s B) 8.0 m/s C) 16 m/s D) 9.8 m/s ____ 90) A girl throws a rock horizontally, with a velocity of 10 m/s, from a bridge. It falls 20 m to the water below. How far does the rock travel horizontally before striking the water, assuming negligible air resistance? A) 14 m B) 16 m C) 20 m D) 24 m ____ 91) The acceleration due to gravity on the Moon is only one-sixth of that on Earth, and the Moon has no atmosphere. If you hit a baseball on the Moon with the same effort (and therefore at the speed and angle) as on Earth, how far would the ball would travel on the Moon compared to on Earth? Neglect air resistance on Earth. A) 1/6 as far as on Earth B) 36 times as far as on Earth C) the same distance as on Earth D) 6 times as far as on Earth E) as far as on Earth ____ 92) A cat leaps to try to catch a bird. If the cat's jump was at 60° off the ground and its initial velocity was A) B) C) D) what is the highest point of its trajectory, neglecting air resistance? 0.29 m 0.58 m 10.96 m 0.19 m ____ 93) A fisherman casts his bait toward the river at an angle of 25° above the horizontal. As the line unravels, he notices that the bait and hook reach a maximum height of What was the initial velocity he launched the bait with? Assume that the line exerts no appreciable drag force on the bait and hook and that air resistance is negligible. A) 18 m/s B) 7.9 m/s C) 7.6 m/s D) 6.3 m/s ____ 94) You throw a rock horizontally off a cliff with a speed of 20 m/s and no significant air resistance. After 2.0 s, the magnitude of the velocity of the rock is closest to A) 28 m/s B) 20 m/s C) 40 m/s D) 37 m/s 95) A batter hits a home run in which the ball travels 110 m horizontally with no appreciable air resistance. If the ball left the bat at 50° above the horizontal just above ground level, how fast was it hit? 96) A girl throws a rock horizontally with a speed of 12 m/s from a bridge. It falls 2.28 s before hitting the water below. Neglect air resistance. (a) How high is the bridge from the water below? (b) How far horizontally does the rock travel before striking the water? 97) A ball rolls over the edge of a platform with a horizontal velocity of magnitude v. The height of the platform is 1.6 m and the horizontal range of the ball from the base of the platform is 20 m. What is the magnitude of v if air resistance is negligibly small? 98) A projectile is shot horizontally at 23.4 m/s from the roof of a building 55 m tall and experiences negligible air resistance. (a) Determine the time necessary for the projectile to reach the ground below. (b) Determine the distance from the base of the building that the projectile lands. (c) Determine the horizontal and vertical components of the velocity just before the projectile reaches the ground. ____ 99) An athlete participates in an interplanetary discus throw competition during an Olympiad that takes place on a planet where the acceleration due to gravity is 9.7 m/s2. He throws the discus with an initial velocity of 20 m/s at an angle of 60° from the vertical. Neglecting air resistance and the height of the discus at the point of release, what is the range of the discus? A) 21 m B) 60 m C) 36 m D) 40 m E) 32 m ____ 100) The horizontal and vertical components of the initial velocity of a football are 16 m/s and 20 m/s respectively. If there is no air resistance, how long does it take the football to reach the top of its trajectory? A) 1.0 s B) 2.0 s C) 3.0 s D) 4.0 s E) 5.0 s ____ 101) A boy kicks a football with an initial velocity of 20 m/s at an angle of 25° above the horizontal. If we neglect air resistance, the magnitude of the acceleration of the ball while it is in flight is A) 25 m/s2. B) 18 m/s2. C) 9.8 m/s2. D) 8.5 m/s2. E) 0 m/s2. 5.1 Conceptual Questions ____ 102) In a collision between a huge SUV and a small hybrid car, the SUV exerts a larger force on the hybrid than the hybrid exerts on the SUV. A) True B) False C) It depends on whether the collision is a head-on collision or a rear-end collision. ____ 103) While flying horizontally in an airplane, you notice that a string dangling from the overhead luggage compartment hangs at rest at 15° away from the vertical toward the front of the plane. Using this observation, you can conclude that the airplane is A) moving forward. B) moving backward. C) accelerating forward. D) accelerating backward. E) not accelerating because the string is at rest. ____ 104) A crate is sliding down an inclined ramp at a constant speed of 0.55 m/s. The vector sum of all the forces acting on this crate must point A) down the ramp. B) up the ramp. C) perpendicular to the ramp. D) vertically downward. E) None of the above choices is correct. ____ 105) A small car and a large SUV are at a stoplight. The car has a mass equal to half that of the SUV, and the SUV can produce a maximum accelerating force equal to twice that of the car. When the light turns green, both drivers push their accelerators to the floor at the same time. Which vehicle pulls ahead of the other vehicle after a few seconds? A) The car pulls ahead. B) The SUV pulls ahead. C) It is a tie. ____ 106) An object is moving with constant non-zero velocity. Which of the following statements about it must be true? A) A constant force is being applied to it in the direction of motion. B) A constant force is being applied to it in the direction opposite of motion. C) A constant force is being applied to it perpendicular to the direction of motion. D) The net force on the object is zero. E) Its acceleration is in the same direction as it velocity. ____ 107) A horse pulls a cart with force . As a result of this force the cart accelerates with constant acceleration. The magnitude of the force that the cart exerts on the horse A) is zero newtons. B) equal to the magnitude of . C) less than the magnitude of . D) greater than the magnitude of . E) cannot be determined without knowing the mass of the horse. ____ 108) A person is using a rope to lower a 5.0-N bucket into a well with a constant speed of 2.0 m/s. What is the magnitude of the force exerted by the rope on the bucket? A) 0.00 N B) 2.0 N C) 5.0 N D) 10 N E) 49 N ____ 109) A person who normally weighs 700 N is riding in an elevator that is moving upward but slowing down at a steady rate. If this person is standing on a bathroom scale inside the elevator, what would the scale read? A) more than 700 N B) less than 700 N C) 700 N D) It could be more or less than 700 N, depending on whether the magnitude of the acceleration is greater than or less than 9.8 m/s2. ____ 110) Inside of a train a ball of weight W is hanging by a light wire at rest from the ceiling. The wire makes an angle θ with the ceiling, as shown in the figure. Which one of the following conditions must be true about the tension T in the wire? A) B) C) D) E) T sin θ = W T cos θ = W T tan θ = W T=W T = ma ____ 111) Two blocks, A and B, are being pulled to the right along a horizontal surface by a horizontal 100-N pull, as shown in the figure. Both of them are moving together at a constant velocity of 2.0 m/s to the right, and both weigh the same. Which of the figures below shows a correct free-body diagram of the horizontal forces acting on the upper block, A? A) B) C) D) E) ____ 112) As shown in the figure, a woman is straining to lift a large crate, but without success because it is too heavy. We denote the forces on the crate as follows: P is the magnitude of the upward force being exerted on the crate by the person, C is the magnitude of the vertical contact force on the crate by the floor, and W is the weight of the crate. How are the magnitudes of these forces related while the person is trying unsuccessfully to lift the crate? A) B) C) D) P+C=W P+C<W P+C>W P=C ____ 113) A push of magnitude P acts on a box of weight W as shown in the figure. The push is directed at an angle below the horizontal, and the box remains a rest. The box rests on a horizontal surface that has some friction with the box. The normal force on the box due to the floor is equal to A) B) C) D) E) W. W + P. W + P cos . W + P sin . W - P sin . 5.2 Problems ____ 114) If I weigh 741 N on Earth at a place where g = 9.80 m/s2 and 5320 N on the surface of another planet, what is the acceleration due to gravity on that planet? A) 70.4 m/s2 B) 51.4 m/s2 C) 61.2 m/s2 D) 81.0 m/s2 ____ 115) An astronaut weighs 99 N on the Moon, where the acceleration of gravity is 1.62 m/s2. How much does she weigh on Earth? A) 16 N B) 61 N C) 99 N D) 600 N E) 440 N ____ 116) A net force of 125 N is applied to a certain object. As a result, the object accelerates with an acceleration of 24.0 m/s2. The mass of the object is A) 3000 kg. B) 2880 kg. C) 144 kg. D) 0.200 kg. E) 5.21 kg. ____ 117) A car of mass 1100 kg that is traveling at 27 m/s starts to slow down and comes to a complete stop in 578 m. What is the magnitude of the average braking force acting on the car? A) 690 N B) 550 N C) 410 N D) 340 N 118) A catcher stops a 0.15-kg ball traveling at 40 m/s in a distance of 20 cm. What is the magnitude of the average force that the ball exerts against his glove? ____ 119) A 1200-kg car is pulling a 500-kg trailer along level ground. Friction of the road on the trailer is negligible. The car accelerates with an acceleration of 1.3 m/s2. What is the force exerted by the car on the trailer? A) 550 N B) 600 N C) 650 N D) 700 N E) 750 N 120) In a certain particle accelerator, a proton reaches an acceleration of 9.0 1013 m/s2. The mass of a proton is 1.67 10-27 kg. What is the force on the proton? 121) A box of mass 72 kg is at rest on a horizontal frictionless surface. A constant horizontal force of magnitude F then acts on the box, accelerating it to the right. You observe that it takes the box 3.4 seconds to travel 13 meters. What is the magnitude of the force F? 122) A 10-kg object is hanging by a very light wire in an elevator that is traveling upward. The tension in the rope is measured to be 75 N. What are the magnitude and direction of the acceleration of the elevator? ____ 123) The figure shows an object's acceleration-versus-force graph. What is the mass of this object? A) B) C) D) 2.5 g 1.6 g 630 g 400,000 g ____ 124) A 50.0-kg crate is being pulled along a horizontal smooth surface. The pulling force is 10.0 N and is directed 20.0° above the horizontal. What is the magnitude of the acceleration of the crate? A) 0.0684 m/s2 B) 0.188 m/s2 C) 0.200 m/s2 D) 0.376 m/s2 E) 0.0728 m/s2 ____ 125) A tightrope walker walks across a 30-m long wire tied between two poles. The center of the wire is displaced vertically downward by 1.0 m when he is halfway across. If the tension in both halves of the wire at this point is what is the mass of the tightrope walker? Neglect the mass of the wire. A) 85 kg B) 43 kg C) 74 kg D) 91 kg 126) A 30.0-kg load is being held in place using massless wires in the ideal pulley arrangement shown in the figure. What is the magnitude of the force F? 127) A very light wire is used to hang a series of 8.0-kg bricks. This wire will break if the tension in it exceeds 450 N. The bricks are hung one below the other from a hook in the ceiling using this wire, as shown in the figure. (a) How many whole bricks can be hung without breaking the wire? (b) If you add one more brick to the number found in part (a), which string will break? 128) A 55-kg box rests on a horizontal surface. The coefficient of static friction between the box and the surface is 0.30, and the coefficient of kinetic friction is 0.20. What horizontal force must be applied to the box to cause it to start sliding along the surface? ____ 129) A baseball player is running to second base at 5.03 m/s. When he is 4.80 m from the plate he goes into a slide. The coefficient of kinetic friction between the player and the ground is 0.180, and the coefficient of static friction is 3.14. What is his speed when he reaches the plate? A) 4.47 m/s B) 2.89 m/s C) 1.96 m/s D) 2.56 m/s E) He stops before reaching the plate. ____ 130) An ornament of mass 40.0 g is attached to a vertical ideal spring with a force constant (spring constant) of 20.0 N/m. The ornament is then lowered very slowly until the spring stops stretching. How much does the spring stretch? A) 0.00200 m B) 0.0196 m C) 0.0816 m D) 0.800 m E) 0.200 m Physics Practice Mid Term Answer Section 1) 2) 3) 4) 5) 6) 7) 8) 9) 10) 11) 12) 13) 14) 15) 16) 17) 18) 19) 20) 21) 22) 23) 24) 25) 26) 27) 28) 29) 30) 31) 32) 33) 34) 35) 36) 37) ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: A A B A B C C A A B D A A E A B D D A B A A B B E A C E A A A A C A D A PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: Var: 1 Var: 50+ Var: 1 Var: 3 Var: 1 Var: 1 Var: 1 Var: 1 Var: 1 Var: 5 Var: 1 Var: 50+ Var: 50+ Var: 1 Var: 11 Var: 1 Var: 1 Var: 1 Var: 50+ Var: 1 Var: 50+ Var: 50+ Var: 1 Var: 1 Var: 1 Var: 1 Var: 1 Var: 1 Var: 1 Var: 50+ Var: 1 Var: 50+ Var: 1 Var: 1 Var: 1 Var: 1 (a) 10.5 km (b) 2.50 km south PTS: 1 38) ANS: B 39) ANS: (a) 0 m/s (b) 4 m/s REF: Var: 1 PTS: 1 REF: Var: 1 PTS: 1 40) ANS: REF: Var: 1 (a) 5.25 km/h (b) 1.25 km/h south PTS: 1 41) ANS: REF: Var: 1 (a) 1.0 m/s (b) 0 m/s PTS: 1 42) ANS: REF: Var: 1 (a) 10 m/s (b) 20 m/s (c) 0 m/s (d) -40 m/s 43) 44) 45) 46) 47) 48) 49) 50) 51) PTS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: 1 B E B A B C B C REF: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: Var: 1 1 1 1 1 1 1 1 1 REF: REF: REF: REF: REF: REF: REF: REF: Var: 1 Var: 1 Var: 1 Var: 1 Var: 1 Var: 1 Var: 1 Var: 1 1 C C A C C D B C REF: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: Var: 1 1 1 1 1 1 1 1 1 REF: REF: REF: REF: REF: REF: REF: REF: Var: 1 Var: 1 Var: 50+ Var: 1 Var: 4 Var: 4 Var: 1 Var: 1 5.6 s 52) 53) 54) 55) 56) 57) 58) 59) 60) PTS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: (a) 10 m/s2 (b) 0 m/s2 PTS: 1 61) ANS: REF: Var: 1 Between 7.0 m and 17.0 m PTS: 1 62) ANS: D 63) ANS: C 64) ANS: REF: Var: 1 PTS: 1 PTS: 1 REF: Var: 1 REF: Var: 1 REF: Var: 1 PTS: 1 REF: Var: 1 (a) B (b) A PTS: 1 65) ANS: D 66) 67) 68) 69) 70) 71) 72) 73) 74) ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: B B C B C A A E (a) 22.6° PTS: 1 75) ANS: (a) 5.00 m PTS: 1 76) ANS: A 77) ANS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: 1 1 1 1 1 1 1 1 REF: REF: REF: REF: REF: REF: REF: REF: Var: 1 Var: 1 Var: 1 Var: 1 Var: 1 Var: 47 Var: 50+ Var: 1 (b) 13.0 m REF: Var: 1 (b) 53.1° REF: Var: 1 PTS: 1 REF: Var: 31 (a) Ax = 65 cm, Ay = 38 cm (b) Bx = -25 cm, By = 0 cm (c) Cx = -28 cm, Cy = -28 cm (d) Rx = 12 cm, Ry = 9 cm (e) 15 cm at 38° above the +x-axis PTS: 1 78) ANS: A 79) ANS: C 80) ANS: REF: Var: 1 PTS: 1 PTS: 1 REF: Var: 1 REF: Var: 1 35 m at 39° north of east PTS: 1 81) ANS: (a) 185 N PTS: 1 82) ANS: REF: Var: 1 (b) 77.8° above the +x-axis REF: Var: 1 -11 cm (x component), -4.5 cm (y component) PTS: 1 83) ANS: REF: Var: 1 0.00 cm (x component), 4.2 cm (y component) PTS: 1 84) ANS: REF: Var: 1 4.2 cm along the +y-axis PTS: 1 85) ANS: REF: Var: 1 100 m at 31° above the +x-axis PTS: 1 86) ANS: D 87) ANS: (a) 20 m 88) 89) 90) 91) 92) 93) 94) 95) PTS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: REF: Var: 1 PTS: 1 REF: Var: 1 (b) 0 m 1 A B C D A A A REF: PTS: PTS: PTS: PTS: PTS: PTS: PTS: Var: 1 1 1 1 1 1 1 1 REF: REF: REF: REF: REF: REF: REF: Var: 2 Var: 1 Var: 1 Var: 1 Var: 50+ Var: 30 Var: 1 33 m/s PTS: 1 96) ANS: (a) 25 m PTS: 1 97) ANS: REF: Var: 1 (b) 27 m REF: Var: 1 35 m/s PTS: 1 98) ANS: (a) 3.4 s 99) 100) 101) 102) 103) 104) 105) 106) 107) 108) 109) 110) 111) 112) 113) 114) 115) 116) PTS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: 1 C B C B D E C D B C B A E A D A D E REF: Var: 1 (b) 78 m (c) vhoriz = 23.4 m/s, vvert = 33 m/s downward REF: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: Var: 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: REF: Var: 1 Var: 1 Var: 1 Var: 1 Var: 1 Var: 1 Var: 1 Var: 1 Var: 1 Var: 1 Var: 1 Var: 1 Var: 1 Var: 1 Var: 1 Var: 50+ Var: 1 Var: 1 117) ANS: A 118) ANS: PTS: 1 REF: Var: 1 REF: Var: 1 PTS: 1 REF: Var: 1 600 N PTS: 1 119) ANS: C 120) ANS: 1.5 10-13 N PTS: 1 121) ANS: REF: Var: 1 160 N PTS: 1 122) ANS: REF: Var: 50+ 2.3m/s2, downward 123) 124) 125) 126) PTS: ANS: ANS: ANS: ANS: 1 A B A REF: PTS: PTS: PTS: Var: 1 1 1 1 REF: Var: 1 REF: Var: 1 REF: Var: 50+ 147 N PTS: 1 127) ANS: REF: Var: 1 (a) 5 (b) the top wire PTS: 1 128) ANS: REF: Var: 1 160 N PTS: 1 129) ANS: B 130) ANS: B REF: Var: 1 PTS: 1 PTS: 1 REF: Var: 1 REF: Var: 1