AP Physics – Chapter 2 and 3 Homework Problems
Ch2 HW#1 p49+ 1,3,4,5,9,18
1. In the next 3.0s, the Earth will travel roughly 885,000m along its orbit around the Sun.
Compute its average orbital speed.
3. Standing on the roof of a building a kid drops a plastic bag filled with water at a height of 100m,
and 4.5s later it strikes the ground. Determine the bag’s average speed.
4. Hair grows at an average rate of 3 x 10-9 m/s. How long will it take to grow a 10cm strand?
5. Given that a glacier creeps along at an average speed of 1 x 10-6 m/s, how long will it take to advance 1.0km?
9. If the odometer in a car at the beginning of a trip read 12723.10km and 2.00hr later it read 12973.10km,
what was the average speed during the journey?
18. To test a small rocket motor it’s fired upward. It rises to a height of 100m in 5.0s and then falls back to the
ground at an average speed of 10.0m/s. How long did the whole trip take, and what was the average speed?
Ch2 HW#2 p50+ 20,21,23,24,25,27,32,33
20. You know how you close your eyes when you sneeze? Suppose you are driving along at a constant
96.5 km/h (i.e. 60 mi/h) and you experience a 1.00s long, eyes-closed, giant sneeze.
How many meters does the car travel while you are out of control?
21. Light travels in a vacuum at a fixed speed of roughly 2.998 x 10 8 m/s and its speed in air is only negligibly
slower (0.03%) than that.
a. How long does it take light to traverse 1 ft (~.30 m)?
b. When you are looking at something 1000m away, you are seeing it as it was ___sec back in time.
23. Figure P23 is a plot of the speed of a cat versus time. How far did the cat
travel during the third second of its journey?
What were its maximum and minimum speeds?
When, if ever, was its speed a nonzero constant?
24. The Earth rotates once around its spin axis at 23 hr 56 min and its
equatorial diameter is 1.276 x 107 m (i.e. 7927 mi).
At what speed would you be traveling with respect to
the stars in Mbandaka, Zaire, on the Equator? Draw a diagram.
25. Use Fig 2.5 (page 26) to calculate the distance traveled by the bee
(whose speed-time graph is plotted) in the time interval
from 1.33 s to 2.83 s.
27. Figure P27 shows the distance traveled versus time for a toy car.
What was the toy car’s average speed during the time interval
from 2.0 s to 8.0 s?
32. Go back up to Fig P23, the plot of the speed of a cat versus time.
Approximately, what was the instantaneous speed at each of
the following times: 0s, 1.0s, 2.0s, 4.5s, 6.0s, and 7.0s?
During what time intervals was the speed increasing?
When was its speed decreasing?
33. While driving along a winding mountain road a passenger makes a plot
of the tripmeter’s readings against time. Placing a dot on the distance
versus time curve every 10.0 s for 5 min, he gets a straight line passing
through the x = 0, t = 0 origin having a slope of 16.0 m/s.
What is the instantaneous speed of the car at 45 s into the exercise?
How far does the car travel in the time between t = 86 s and t = 186 s?
Ch2 HW#3 p50+ 36,38,40,42,53,59,60
36. A mouse runs straight north 1.414m, stops, turns right through 90°, and runs another 1.414m due east.
Through what distance is it displaced? Draw a diagram.
38. A youngster on a roof of a 19.0m tall building stands at the edge and throws a paper plane from a height of
1.00m above the roof. It sails around before landing directly in front of him 15.0m from the building. What
is the magnitude of the displacement of the plane from its landing point? Draw a diagram.
40. After lifting off its launch pad, a rocket is found to be 480m directly above an observer who is 360m due
east of the pad. What is the displacement of the rocket from the pad at that moment? Draw a diagram.
42. A jogger in the city runs 4 blocks north, 2 blocks east, 1 block south, 4 blocks west, 1 block north, 1 block
west, and collapses. Determine the magnitude of the jogger’s displacement. Draw a diagram.
53. A cannonball fired from a gun at ground level located 20m away from a castle rises high into the air in a smooth
arc and sails down, crashing into the wall 60m up from the ground. Determine the projectile’s displacement.
59. A bumblebee flew 43m along a twisting path only to land on a flower 3.0m due south of the point on its hive
from which it started. If the entire journey took 10s, what was its average speed and average velocity?
60. While on vacation a tourist left the center of town in a rented car having an odometer reading of 26725.10km.
He traveled south of west for 6.00hr and then swung northeast for 14.0hr, ending up 420km due east of the
center of town. At that point the odometer reading was 27725.10km. Compute ave velocity and ave speed.
Ch2 HW#6 p52+ 71,78,81,87,93,97
71. A toy electric train runs along a straight length of track. Its displacement versus
time curve is shown. Is the train’s velocity ever constant and it so, when?
What is its instantaneous velocity at t = 2.0s and at t = 6.5s?
Did it change direction if so, when?
78. A trolley runs along a straight run of track the graph is the plot of its velocity
versus time. Approximately how far did it travel in the first 3.0s of its journey?
How far from its starting point is it at t = 6.0s?
81. Each of two runners at either end of a 100m straight track jogs toward each other
at a constant 5.0 m/s. How long will it take before they meet?
87. Pennsylvania Avenue and Prince Street intersect at right angles.
If Mary is running at 8.0 m/s northwest toward the intersection along the avenue, and
John is heading northeast at 6.0 m/s toward the intersection
along the street, what is the speed of either person with respect to each other?
93. A hawk 50m above the ground sees a mouse directly below running due north at 2.0 m/s. If it reacts
immediately, at what angle and speed must the hawk dive in a straight line, keeping a constant velocity, to
intercept its prey in 5.0s? Incidentally, the mouse escaped by jumping in a hole.
95. At times of flood, the Colorado River reaches a speed of 48 km/hr near the Lava Falls. Suppose you wanted
to cross it there perpendicularly, in a motorboat capable of traveling at 48 km/hr in still water.
(a) Is it possible? Explain. (b) If on a quieter day the water flows at 32 km/hr, at what angle would you head
the boat to cut directly across the river? (c) At what speed with respect to the shore would you be traveling?
97. A cruise ship heads 30º W of N at 20 km/hr in a still sea. Someone in a sweatshirt dashes across the deck
traveling 60º E of N at 10 km/hr. What was the jogger’s velocity with respect to the Earth?
Ch3 HW#1 p79+ 1,2,3,8,16,18,19,20,21,27
1. A rocket lifts off its launch pad and travels straight up attaining a speed of 100 m/s in 10s.
Calculate its average acceleration.
2. A canvasback duck heading south at 50 km/h at 2:02 A.M. is spotted at 2:06 A.M. still traveling south but at
40 km/h. Calculate its average acceleration over that interval, both magnitude and direction.
3. An android on guard duty in front of the Institute of Robotics is heading due south at 1:07 P.M. at a speed of
10m/s when it receives a command to alter course. At 1:09 P.M. it is recorded to be moving at 10 m/s due
north. Compute its average acceleration over that interval—magnitude and direction.
8. During a typical launch, the space shuttle goes from a vertical speed of 5.75 m/s at t = 1.20 sec to a vertical
speed of 6.90 m/s at t = 1.60 sec, while rising 2.30 m. Determine the average acceleration, both magnitude
and direction.
16. Two motorcycle stuntpersons are driving directly at each other, each having started from rest and each
accelerating at an average rate of 5.5 m/s 2. At what speed will they be approaching each other 2.0 sec into
this lunacy?
18. Figure P18 is a velocity-time graph for a test car on a straight track.
The test car initially moved backward in the negative x-direction
at 20 m/s. It slowed, came to a stop, and then moved off in the
positive x-direction at t = 2.0 s. What was its average acceleration
during each of the time intervals 0 to 0.5s, 1.5 to 2.0s, 2.0 to 2.5s?
What was its instantaneous acceleration at t = 2.25 s?
19. In Figure P18, what was the car’s inst acceleration at t = 3.0s?
Is the instantaneous acceleration positive or negative at t = 3.7s?
How about at t = 1.1s?
What is the instantaneous acceleration of the car at t = 0.25 s?
20. Figure P20 shows the speed-time curves of 3 cyclists traveling a straight
course. What are their respective instantaneous speeds at t = 2s?
Which if any starts out at t = 2s with the greatest instantaneous acceleration?
21. Using figure P20, which cyclist has the greatest inst acceleration
at each of the following times, t = 2.1s, 3.3s, and 6.5s?
27. Using fig 3.3, graphically determine the car’s approximate acceleration
at 3.8s into the run.
Ch3 HW#2 p 80+ 32,33,41,42,43
32. An R75 maintenance robot on a spaceship is standing in front of the bathroom when it begins to move down
the straight passage way. It accelerates at a constant 2.0 m/s2. Find its speed at the end of 5.0 s.
33. With the previous problem in mind, how far did the robot travel in 5.0 s?
41. A good male sprinter can run 100 m in 10 s. What is his average speed?
He will typically reach a peek speed of 11 m/s at about 5 s and slow down toward the finish.
Assuming his acceleration is fairly constant for the first 5 s, how fast will he be going 3 s into the race?
42. If a van moving at 50.0 km/h uniformly accelerates up to 70.0 km/h in 20.0 s, how far along
the straight road will it travel in the process?
43. Supposing that the acceleration of a 1997 Corvette is constant (which it really isn’t) how much road
will it travel in going from 0 to 60 mph ( i.e., 26.8 m/s) in 4.8 s?
Ch3 HW#3 pg 81 46,47,49,53,55,57,64,70
46. The driver of a car traveling at 10.0 m/s along a straight road depresses the accelerator and uniformly
increases her speed at a rate of 2.39 m/s2 straight toward a wall 10m away.
At what speed will it crash into the wall?
47. The length of a straight tunnel through a mountain is 25.9 m. A cyclist heads directly toward it, ccelerating
at a constant rate of 0.20 m/s 2. If at the instant he enters the tunnel he is traveling at a speed of 5.00 m/s,
how fast will he be moving as he emerges?
49. A Jaguar in an auto accident in England in 1960 left the longest recorded skid marks on a public road:
an incredible 290 m long. As we will see later, the friction force between the tires and the pavement
varies with speed, producing a deceleration that increases as the speed decreases. Assuming an average
acceleration of –3.9 m/s2 (that is, -0.4 g), calculate the Jag’s speed when the brakes locked.
53. A driver traveling at 60km/h sees a chicken dash out onto the road and slams on the brakes. Accelerating
at -7 m/s2, the car stops just in time 23.3 m down the road. What was the driver’s reaction time
(i.e., the time that elapsed before he engaged the brake)?
55. A swimmer stroking along at a fast 2.2 m/s ceases all body movement and uniformly coasts to a dead stop
in 10 m. Determine how far she moved during her 3rd second of drift.
57. Two trains heading straight for watch other on the same track are 250 m apart when their engineers see
each other and hit the brakes. The Express, heading west at 96 km/h, slows down, decelerating at an
average of 4 m/s2 while the eastbound Flyer, traveling at 110 km/h, slows down, decelerating at an average
of 3 m/s2. Will they collide?
64. While making a movie, a cowboy on a horse rides up to a moving train traveling at 5.0 km/h along a long
straight length of track. After running next to the last car for a while, he charges ahead toward the engine
100 m away and gets there in 1.10 min. Assuming it was constant, determine the acceleration.
70. A motorcycle cop, parked at the side of a highway reading a magazine, is passed by a woman in a red
Ferrari 308 GTS doing 90.0 km/h. (Divide by 3.6 to get m/s.) After a few attempts to get his cycle started,
the officer roars off 2.00 s later. At what average rate must he accelerate if 110 km/h is his top speed and
he is to catch her just at the state line 2.00 km away?
Ch3 HW#4 Motion Eqns WS
1. What is the velocity of a car that starts at rest, and accelerates at a constant 5 m/s2 for 5 sec?
2. What is the velocity of a car that starts at rest, and accelerates at a constant 5 m/s 2 for 20 m?
3. What is the displacement of an object that starts with an initial velocity of 10 m/s and undergoes
a constant acceleration of 2 m/s2 for 4 sec?
4. If a bicyclist accelerates at a steady rate to finish the sprint at 25 m/s and had an average velocity
of 18 m/s over the sprint, what was his initial velocity?
5. An object is dropped from the top of a building 35 m tall. If it accelerates at 9.8 m/s 2,
neglecting air friction, how long will it take for it to hit the ground?
6. In the last problem, how fast is the object going right before it hits the ground?
7. If you are curious about the depth of a mine shaft, old timers will tell you to drop a rock in the shaft
and time until you hear the rock hit the bottom. If the acceleration of gravity, g, is 9.8 m/s 2 and the rock
falls for 3.5 sec, roughly how deep is the hole?
Ch3 HW#5 p82+ 71 – 75
71. EXPLORING PHYSICS ON YOUR OWN: ask a friend to hold his or her thumb and forefinger parallel to each
other in a horizontal plane. The fingers should be about an inch apart. Now you hold a 1-ft ruler vertically in
the gap just above and between them. Have your friend look at the ruler and catch it when you, without
warning, let it fall. Calculate the corresponding response time. Now position a dollar bill vertically so that
Washington’s face is between your friend’s fingers-is it likely to be caught when dropped?
72. A kangaroo can jump strait up about 2.5 m. What is it’s takeoff speed?
73. At what speed would you hit the floor if you stepped off a chair 0.50 m high? Ignore friction.
74. If a stoned dropped (not thrown) from a bridge takes 3.7 s to hit the water, how high is the rock-dropper?
Ignore friction.
75. Ignoring air fiction, how fast will an object be moving and how far will it have fallen after dropping from rest
for 1.0 s, 2.0 s, 5.0 s, and 10 s?
Ch3 HW#6 Free Fall Worksheet
1. An object is dropped from a height of 50 m. If air resistance is negligible, how long will it take to
hit the ground?
2. An object is dropped from a height of 100 m. If air resistance is negligible, how long will it take to
hit the ground?
3. How do the times compare when dropped from 50 m and 100 m?
4. An object is dropped from an unknown height and falls for 1.3 sec. If air resistance is negligible,
how tall is the height of the drop?
5. An object is dropped from an unknown height and falls for 2.6 sec. If air resistance is negligible,
how tall is the height of the drop?
6. How do the heights differ when the time doubles?
Ch3 HW#7 pg 82+ 76,77,81,82,88,89
76. A cannonball is fired straight up at a rather modest speed of 9.8m/s. Compute its maximum altitude and
the time it takes to reach that height.
77. Calculate the speed at which hailstone, falling from 0.9144x10 4 m out of a cumulonimbus cloud, would
strike the ground, presuming air friction is negligible (which it certainly is not.) Give your answer in m/s.
81. A young kid with a huge baseball cap is playing catch with himself by throwing a ball straight up. How fast
does he throw if the ball comes back to his hands a second later? At low speeds air friction is negligible.
89. A bag of sand dropped by a would-be assassin from the roof of a building just misses Tough Tony, a gangster
2 m tall. The missile traverses the height of Tough Tony in 0.20 s, landing with a thud at his feet.
How high was the building? Ignore friction.
Ch3 HW#8 p82+ 90,92,93,99
90. (Modified) A shoe is flung horizontally at 6.0 m/s, and hits the ground 1.0 sec later.
What vertical height was it thrown from? What horizontal distance will it travel?
92. Suppose you point a rifle horizontally directly at the center of the paper target 100 m away from you.
If the muzzle speed of the bullet is 100 m/s, where will it strike the target?
93. A raw egg is thrown horizontally straight out of the open window of a fraternity house.
If its initial speed is 20 m/s and it hits ground 2.0 s later, at what height was it launched?
99. Two diving platforms 10 m high terminate just at the edge of each end of a swimming pool 30 m long.
How fast must two clowns run straight off their respective boards if they are to collide at the surface of the
water midpool?
Ch3 HW#9 1 – 3
1. A cannonball is fired at 100 m/s at 30°. If air resistance is negligible, how much time elapses until it hits
the ground at the same height it was launched?
2. That cannonball fired at 100 m/s at 30°, how far will it travel?
3. A football is kicked by a punter with an initial speed of 25 m/s at 40°, how far will it travel?
Ch3 HW#10 4 – 6
4. Cannonball fired
5. Cannonball fired
6. Cannonball fired
7. Cannonball fired
at
at
at
at
50
50
50
50
m/s
m/s
m/s
m/s
straight up, how much time and how far?
at 30°, how much time and how far?
at 60°, how much time and how far?
at 45°, how much time and how far?
Ch3 HW#11 p83+ 101,102,107
101. A silver dollar is thrown downward at an angle of 60.0° below the horizontal from the bridge 50.0 m
above a river. If its initial speed is 40.0 m/s, how far from the base of the bridge will it strike the water?
102. Someone at a 3rd floor window (12m above ground) hurls a ball downward at an angle of 45°
at a speed of 25m/s. What speed does it hit the ground?
107. A burning firecracker is tossed into the air at an angle of 60° up from the horizon. If it leaves the
hand of the hurler at the speed of 30 m/s, how long should the fuse be set to burn if the explosion is to occur
20 m away. Ignoring friction, just set up the equation for t.
Ch3 Review p79+ 4,36,58,83,94
4. The 1997 Corvette goes from 0 to 60 mph (i.e., 26.8 m/s) in 4.8 s. What is its average acceleration?
36. Slamming on the brakes, a driver decelerates her car from 25.0 m/s to 15.0 m/s in 3.5 s.
Find her average speed assuming the acceleration was uniform.
58. The drivers of two cars in a demolition derby are at rest 100 m apart. A clock on a billboard reads
12:17:00 at the moment they begin heading straight toward each other. If both are accelerating at a
constant 2.5 m/s2, at what time will they collide?
83. A lit firecracker is shot straight up at 50.00 m/s. How high is it above ground level 5.000 s later when it
explodes? How fast is it moving when it blows up? How far has it fallen, if at all, from its maximum height?
94. While rolling marbles on a horizontal window sill, a youngster accidentally shoots one at 3.0 m/s out the
open window. He sees it land in a flower pot on a neighbor’s fire escape 3.0 s later.
How far beneath the sill is the pot?