In this version the first answer is the correct one. The first 30 problems are 10 exam problems each of
which have 3 versions. Make sure you compare with the numbers that you had in the exam. Complete
solutions are at the end of the document.
Instructor: Ihas/Biswas
PHYSICS DEPARTMENT
77777
PHY 2053
Exam 2, 120 minutes
Name (print, last first):
77777
November 14, 2008
Signature:
On my honor, I have neither given nor received unauthorized aid on this examination.
DIRECTIONS
(1) Code your test number (THE 5-DIGIT NUMBER AT THE TOP OF EACH PAGE) on your answer
sheet using lines 76–80. Write your test number down and take it with you. Code your name on your answer
sheet. Code your UFID number on your answer sheet.
(2) Print your name on this sheet and sign it also.
(3) You may do scratch work anywhere on this exam. Circle your answers on the test form. At the end of the test,
this exam printout is to be turned in. No credit will be given without both answer sheet and printout.
(4) Fill in the circles of your intended answers completely on the answer sheet, using a #2 pencil or blue or
black ink. Do not make any stray marks or some answers may be counted as incorrect.
(5) The answers are rounded off. Choose the closest to exact. There is no penalty for guessing.
(6) Hand in the answer sheet separately, showing your UFID.
Useful information:
g = 9.80 m/s2
Neglect air resistance.
All ropes and strings are massless.
1. A 0.010 kg bullet traveling horizontally at 400.0 m/s strikes a 4.0 kg block of wood sitting at the edge of a table. The
bullet is lodged into the wood. If the table height is 1.2 m, how far from the table does the block hit the floor? Ignore
friction between the block and table.
(1) 0.49 m
(2) 0.70 m
(3) 0.86 m
(4) 2.4 m
(5) 4.0 m
2. A 0.010 kg bullet traveling horizontally at 400.0 m/s strikes a 4.0 kg block of wood sitting at the edge of a table. The
bullet is lodged into the wood. If the table height is 2.4 m, how far from the table does the block hit the floor? Ignore
friction between the block and table.
(1) 0.70 m
(2) 0.49 m
(3) 0.86 m
(4) 2.4 m
(5) 4.0 m
3. A 0.010 kg bullet traveling horizontally at 400.0 m/s strikes a 4.0 kg block of wood sitting at the edge of a table. The
bullet is lodged into the wood. If the table height is 3.6 m, how far from the table does the block hit the floor? Ignore
friction between the block and table.
(1) 0.86 m
(2) 0.49 m
(3) 0.70 m
(4) 2.4 m
(5) 4.0 m
4. A rifle with a weight of 25.0 N fires a 3.00 g bullet with a speed of 240 m/s. What is the recoil speed of the rifle?
(1) 0.282 m/s
(2) 0.474 m/s
(3) 0.647 m/s
(4) 0.840 m/s
(5) 0.960 m/s
5. A rifle with a weight of 30.0 N fires a 5.00 g bullet with a speed of 290 m/s. What is the recoil speed of the rifle?
(1) 0.474 m/s
(2) 0.282 m/s
(3) 0.647 m/s
(4) 0.840 m/s
(5) 0.960 m/s
6. A rifle with a weight of 25.0 N fires a 5.50 g bullet with a speed of 300 m/s. What is the recoil speed of the rifle.
(1) 0.647 m/s
(2) 0.282 m/s
(3) 0.474 m/s
(4) 0.840 m/s
(5) 0.960 m/s
7. A 10.0 g object moving to the right at 22.0 cm/s makes an elastic head-on collision with a 15.0 g object moving in the
opposite direction at 31.0 cm/s. What is the speed (in cm/s) of the 10.0 g object after the collision?
(1) 41.6 cm/s
(2) 35.4 cm/s
(3) 47.8 cm/s
(4) 22.0 cm/s
(5) 44.0 cm/s
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8. A 10.0 g object moving to the right at 15.0 cm/s makes an elastic head-on collision with a 15.0 g object moving in the
opposite direction at 27.0 cm/s. What is the speed (in cm/s) of the 10.0 g object after the collision?
(1) 35.4 cm/s
(2) 41.6 cm/s
(3) 47.8 cm/s
(4) 22.0 cm/s
(5) 44.0 cm/s
9. A 10.0 g object moving to the right at 23.0 cm/s makes an elastic head-on collision with a 15.0 g object moving in the
opposite direction at 36.0 cm/s. What is the speed (in cm/s) of the 10.0 g object after the collision?
(1) 47.8 cm/s
(2) 35.4 cm/s
(3) 41.6 cm/s
(4) 22.0 cm/s
(5) 44.0 cm/s
10. A coin with a diameter of 2.40 cm is dropped on edge onto a horizontal surface. The coin starts out with an initial
angular speed of 15.9 rad/s and rolls in a straight line without slipping. If the rotation slows with an angular acceleration
of magnitude 2.19 rad/s2 , how far does the coin roll before coming to rest?
(1) 0.693 m
(2) 1.20 m
(3) 0.401 m
(4) 2.40 m
(5) 15.9 m
11. A coin with a diameter of 3.40 cm is dropped on edge onto a horizontal surface. The coin starts out with an initial
angular speed of 16.7 rad/s and rolls in a straight line without slipping. If the rotation slows with an angular acceleration
of magnitude 1.97 rad/s2 , how far does the coin roll before coming to rest?
(1) 1.20 m
(2) 0.693 m
(3) 0.401 m
(4) 2.40 m
(5) 15.9 m
12. A coin with a diameter of 1.50 cm is dropped on edge onto a horizontal surface. The coin starts out with an initial
angular speed of 14.4 rad/s and rolls in a straight line without slipping. If the rotation slows with an angular acceleration
of magnitude 1.94 rad/s2 , how far does the coin roll before coming to rest?
(1) 0.401 m
(2) 1.20 m
(3) 0.693 m
(4) 2.40 m
(5) 15.9 m
13. A spring (k = 400 N/m) is compressed 7.1 cm. It is used to push a 0.50 kg block 50 cm along a horizontal frictionless
track and then up a θ = 30◦ incline which has a kinetic friction coefficient of 0.10. How high (vertically) above the track
does the block rise?
(1) 0.18 m
(2) 0.22 m
(3) 0.26 m
(4) 0.27 m
(5) 0.31 m
14. A spring (k = 500 N/m) is compressed 7.1 cm. It is used to push a 0.50 kg block 50 cm along a horizontal frictionless
track and then up a θ = 30◦ incline which has a kinetic friction coefficient of 0.10. How high (vertically) above the track
does the block rise?
(1) 0.22 m
(2) 0.18 m
(3) 0.26 m
(4) 0.27 m
(5) 0.31 m
15. A spring (k = 600 N/m) is compressed 7.1 cm. It is used to push a 0.50 kg block 50 cm along a horizontal frictionless
track and then up a θ = 30◦ incline which has a kinetic friction coefficient of 0.10. How high (vertically) above the track
does the block rise?
(1) 0.26 m
(2) 0.22 m
(3) 0.18 m
(4) 0.27 m
(5) 0.31 m
16. A solid ball of radius R = 10 cm (I = (2/5)M R2 ) rolls 2.00 m down along an incline tilted at 30 degrees to the horizontal
to a flat section. At what speed does it leave the incline?
(1) 3.74 m/s
(2) 4.58 m/s
(3) 5.92 m/s
(4) 8.37 m/s
(5) 6.48 m/s
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17. A solid ball of radius R = 10 cm (I = (2/5)M R2 ) rolls 3.00 m down along an incline tilted at 30 degrees to the horizontal
to a flat section. At what speed does it leave the incline?
(1) 4.58 m/s
(2) 3.74 m/s
(3) 5.92 m/s
(4) 8.37 m/s
(5) 6.48 m/s
18. A solid ball of radius R = 10 cm (I = (2/5)M R2 ) rolls 5.00 m down along an incline tilted at 30 degrees to the horizontal
to a flat section. At what speed does it leave the incline?
(1) 5.92 m/s
(2) 4.58 m/s
(3) 3.74 m/s
(4) 8.37 m/s
(5) 6.48 m/s
19. At what speed will a 10,000 N car round a 52-m-radius curve, banked at a 45◦ angle, if no friction is required between
the road and tires to prevent the car from slipping?
(1) 23 m/s
(2) 17 m/s
(3) 27 m/s
(4) 35 m/s
(5) 52 m/s
20. At what speed will a 10,000 N car round a 30-m-radius curve, banked at a 45◦ angle, if no friction is required between
the road and tires to prevent the car from slipping?
(1) 17 m/s
(2) 23 m/s
(3) 27 m/s
(4) 35 m/s
(5) 52 m/s
21. At what speed will a 10,000 N car round a 74-m-radius curve, banked at a 45◦ angle, if no friction is required between
the road and tires to prevent the car from slipping?
(1) 27 m/s
(2) 17 m/s
(3) 23 m/s
(4) 35 m/s
(5) 52 m/s
22. A roller coaster, loaded with passengers, has a mass of 2 000 kg; the radius of curvature of the track at the bottom point
of the dip is 24 m. If the vehicle has a speed of 18 m/s at this point, what force is exerted on the vehicle by the track?
(1) 4.7 × 104 N
(2) 2.3 × 104 N
(3) 7.0 × 104 N
(4) 1.0 × 104 N
(5) 1.8 × 104 N
23. A roller coaster, loaded with passengers, has a mass of 1 000 kg; the radius of curvature of the track at the bottom point
of the dip is 24 m. If the vehicle has a speed of 18 m/s at this point, what force is exerted on the vehicle by the track?
(1) 2.3 × 104 N
(2) 4.7 × 104 N
(3) 7.0 × 104 N
(4) 1.0 × 104 N
(5) 1.8 × 104 N
24. A roller coaster, loaded with passengers, has a mass of 3 000 kg; the radius of curvature of the track at the bottom point
of the dip is 24 m. If the vehicle has a speed of 18 m/s at this point, what force is exerted on the vehicle by the track?
(1) 7.0 × 104 N
(2) 2.3 × 104 N
(3) 4.7 × 104 N
(4) 1.0 × 104 N
(5) 1.8 × 104 N
25. An object when orbiting the Earth at a height of three Earth radii from the center of the Earth has a weight of 1.00 N.
What is the object’s mass? (g at the surface of the Earth is 9.80 m/s2 )
(1) 0.920 kg
(2) 1.84 kg
(3) 2.76 kg
(4) 0.306 kg
(5) 0.102 kg
26. An object when orbiting the Earth at a height of three Earth radii from the center of the Earth has a weight of 2.00 N.
What is the object’s mass? (g at the surface of the Earth is 9.80 m/s2 )
(1) 1.84 kg
(2) 0.920 kg
(3) 2.76 kg
(4) 0.306 kg
(5) 0.102 kg
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27. An object when orbiting the Earth at a height of three Earth radii from the center of the Earth has a weight of 3.00 N.
What is the object’s mass? (g at the surface of the Earth is 9.80 m/s2 )
(1) 2.76 kg
(2) 1.84 kg
(3) 0.920 kg
(4) 0.306 kg
(5) 0.102 kg
28. A vault is opened by applying a force of 300 N perpendicular to the plane of the door, 0.800 m from the hinges. Find
the torque due to this force about an axis through the hinges.
(1) 240 N·m
(2) 120 N·m
(3) 480 N·m
(4) 300 N·m
(5) 360 N·m
29. A vault is opened by applying a force of 150 N perpendicular to the plane of the door, 0.800 m from the hinges. Find
the torque due to this force about an axis through the hinges.
(1) 120 N·m
(2) 240 N·m
(3) 480 N·m
(4) 300 N·m
(5) 360 N·m
30. A vault is opened by applying a force of 600 N perpendicular to the plane of the door, 0.800 m from the hinges. Find
the torque due to this force about an axis through the hinges.
(1) 480 N·m
(2) 120 N·m
(3) 240 N·m
(4) 300 N·m
(5) 360 N·m
31. An 80-kg man is one fourth of the way up a 10-m uniform ladder that is resting against a smooth, frictionless wall. If
the ladder has a mass of 20 kg and it makes an angle of 60◦ with the ground, find the force of friction of the ground on
the foot of the ladder.
(1) 1.7 × 102 N
(2) 2.0 × 102 N
(3) 50 N
(4) 7.8 × 102 N
(5) 25 N
32. A 4.2-kg mass is placed at (3.0, 4.0) m. Where can an 8.4-kg mass be placed so that the moment of inertia about the
z-axis is zero?
(1) There is no position giving this result. (2) (-3.0, -4.0) m (3) (-6.0, -8.0) m (4) (-1.5, -2.0) m (5) (0.0, 0.0) m
33. An object with mass m and moment of inertia I is spinning with an angular momentum L. Its kinetic energy is:
(1) 0.5L2 /I
(2) 0.5I 2 /L
(3) 0.5L2 /m
(4) 0.5I 2 /m
(5) 0.5L2 /I 2
34. A bucket of water with total mass 23 kg is attached to a rope, which in turn is wound around a 0.050-m radius cylinder
at the top of a well. A crank with a turning radius of 0.25 m is attached to the end of the cylinder and the moment
of inertia of cylinder and crank is 0.12 kg·m2 . If the bucket is raised to the top of the well and released, what is the
acceleration of the bucket as it falls toward the bottom of the well? (Assume that cylinder turns on frictionless bearings.)
(1) 3.2 m/s2
(2) 6.3 m/s2
(3) 7.4 m/s2
(4) 9.8 m/s2
(5) 4.9 m/s2
35. Two point particles A and B of equal mass are located at some distance from each other. Particle A is at rest while B
moves away from A at speed v. What happens to the center of mass of the system of two particles?
(1)
(2)
(3)
(4)
(5)
It
It
It
It
It
moves with speed
does not move
moves with speed
moves with speed
moves with speed
v/2 away from A
v away from A
v toward A
v/2 toward A
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36. A wheel is rotating around a fixed axis at constant angular velocity. Which one of the following statements is true?
(1)
(2)
(3)
(4)
(5)
The tangential speed of a point on the rim is constant
The tangential velocity of a point on the rim is constant
Every point on the rim has a tangential acceleration
The angular speed of the wheel is not constant
None of the other statements are true
37. A system is composed of 4 particles situated at the corners of a rectangle with width 10.0 cm and height 6.00 cm. The
masses are 1.00 g (lower left corner), 2.00 g (upper left corner), 3.00 g (lower right corner), and 4.00 g (upper right
corner). What is the distance of the Center of Gravity of this system from the largest mass.
(1) 3.84 cm
(2) 6.00 cm
(3) 10.0 cm
(4) 5.83 cm
(5) 0.00 cm
38. When we are in a car traveling on a curve we feel an outward force away from the center of the curve. In which direction
does the centripetal acceleration point?
(1)
(2)
(3)
(4)
(5)
Inwards toward the center of the curve.
Outwards from the center of the curve
Opposite to the direction of motion.
In the direction of motion.
Along the bank of the curve.
39. Two rigid objects have the same mass, radius, and angular speed about their central axis. One is a solid sphere
(I = (2/5)M R2 ) and the other is a hollow sphere (I = (2/3)M R2 ). If the same braking torque is applied to each, which
takes longer to stop?
(1)
(2)
(3)
(4)
(5)
Hollow sphere
Solid sphere
Both stop in the same time
Not enough information
Conservation of angular momentum does not apply.
40. A figure skater on ice with arms extended, spins at a rate of 2.5 rev/s. After he draws his arms in, he spins at 6.0 rev/s.
By what factor does the skater’s kinetic energy change when he draws his arms in?
(1) 2.4
(2) 1.0
(3) 0.42
(4) 0.12
(5) 4.8
FOLLOWING GROUPS OF QUESTIONS WILL BE SELECTED AS ONE GROUP FROM EACH TYPE
TYPE 1
Q# S 1
Q# S 2
Q# S 3
TYPE 2
Q# S 4
Q# S 5
Q# S 6
TYPE 3
Q# S 7
Q# S 8
Q# S 9
TYPE 4
Q# S 10
Q# S 11
Q# S 12
TYPE 5
Q# S 13
Q# S 14
Q# S 15