Physics 110 Name_____________________________
Exam #1
September 13, 1996
USEFUL INFORMATION
|
q
|
30°
|
37°
|
45°
|
53°
|
60°
|
|
sin q
|
0.5
|
0.6
|
0.707
|
0.8
|
0.866
|
|
cos q
|
0.866
|
0.8
|
0.707
|
0.6
|
0.5
|
|
tg q
|
0.58
|
0.75
|
1.0
|
1.33
|
1.73
|
Please use g = 10 m/sec2
1. A student walks at a constant speed of 5 m/sec. How long does it take her to travel 2 km? (1 km = 1000 m)
1) 400 sec
2) 800 sec
3) 1600 sec
4) 3200 sec
5) 4000 sec
2. Convert 88 ft/sec to units of meters per second. (1 m = 3.28 ft)
1) 18.3 m/sec
2) 26.8 m/sec
3) 60 m/sec
4) 196.8 m/sec
5) 288.6 m/sec
3. Consider these three cases:
A runner accelerates from rest to 5 m/sec in 2 seconds.
A truck accelerates from 10 m/sec to 20 m/sec in 2 seconds.
A car accelerates from 20 m/sec to 40 m/sec in 4 seconds.
Which statement is TRUE?
1) All three have the same acceleration.
2) The car accelerates faster than the truck.
3) The acceleration of the runner is 10 m/sec2.
4) The acceleration of the car is 10 m/sec2.
5) The car and the truck have the same acceleration.
4. Acceleration is the:
1) rate at which distance is covered.
2) the change in distance.
3) the change in velocity.
4) the rate at which velocity changes.
5) the change in speed.
5. A runner accelerates from rest to 15 m/sec in 3 seconds. What is his acceleration?
1) zero
2) 3.3 m/sec2
3) 5 m/sec2
4) 30 m/sec2
5) 45 m/sec2
6. A truck moves at constant acceleration. It passes one point with a velocity of 20 m/sec and then passes a second point ten seconds later at a velocity of 30 m/sec. What is the distance between these two points?
1) 50 m
2) 100 m
3) 200 m
4) 250 m
5) 300 m
7. An object moves with constant velocity. Which statement is FALSE?
1) The speed is constant.
2) The direction is not changing.
3) The acceleration is zero.
4) The object is in free fall.
8. Calculate the acceleration of a runner if he increases his speed from rest to 6 m/sec over a distance of 9 meters.
1) 0.33 m/sec2
2) 2 m/sec2
3) 3 m/sec2
4) 4 m/sec2
5) 6.75 m/sec2
9. A ball is thrown upward with an initial velocity of 40 m/sec. How high will it rise?
1) 2 m
2) 20 m
3) 25 m
4) 40 m
5) 80 m
10. A ball is dropped from a tall building. What distance does it travel in the first three seconds?
1) 15 m
2) 30 m
3) 45 m
4) 60 m
5) 90 m
11. A ball is thrown upwards. After it leaves the hand and is in free fall, the acceleration of the ball:
1) increases and then decreases.
2) decreases.
3) is zero.
4) increases.
5) is constant.
12. A ball is dropped from a tall building. What is its speed after four seconds of free fall?
1) 2.5 m/sec
2) 10 m/sec
3) 20 m/sec
4) 25 m/sec
5) 40 m/sec
13. A ball is thrown down from a tall building with an initial velocity of 20 m/sec. What is its speed after four seconds of free fall?
1) 10 m/sec
2) 20 m/sec
3) 50 m/sec
4) 60 m/sec
5) 80 m/sec
14. The flights of three balls are shown below. Ball A is thrown straight up; ball B is thrown at an angle of 60E above the horizontal; and ball C is thrown at an angle of 30E above the horizontal. All three balls are released at the same time and all three balls rise to the same height. Which statement is FALSE?
1) All three reach the maximum
height at the same time.
2) All three have the same component
of initial vertical velocity.
3) Ball three has the greatest initial velocity.
4) In flight, the acceleration of all three balls
is the same.
5) Ball A returns to the original vertical
position before the other two balls.
Problems 15-17 refer to the situation in the figure below.
Ball is rolling on the table with a horizontal velocity of 10 m/sec.
15. At the instant the ball leaves the table the horizontal velocity is:
1) zero
2) 5 m/sec
3) 10 m/sec
4) 20 m/sec
5) 40 m/sec
16. Which of the following would increase the amount of time that the ball is in the air?
1) Increasing the speed of the ball as it rolls on the table.
2) Decreasing the speed of the ball as it rolls on the table.
3) Lowering the table.
4) Raising the table.
5) Performing this experiment on the planet Jupiter where the acceleration of gravity is 26.4 m/sec2.
17. How long is the ball in the air?
1) 0.2 sec
2) 0.4 sec
3) 0.5 sec
4) 0.8 sec
5) 4.0 sec
Problems 18-19 refer to the situation described below:
A ball is thrown with an initial velocity of 100 m/sec at an angle of 53E above the horizontal. The initial horizontal velocity is 60 m/sec and the initial vertical velocity is 80 m/sec.
18. At point T (the top point of the trajectory) what is the speed of the ball?
1) Zero
2) 30 m/sec
3) 60 m/sec
4) 80 m/sec
5) 100 m/sec
19. How long does it take the ball to reach point T?
1) 3 sec
2) 4 sec
3) 6 sec
4) 8 sec
5) 10 sec
20. A golfer hits a drive off the tee. The initial velocity of the golfball as it leaves the tee is 120 ft/sec at an angle of 15E above the horizontal. What is the horizontal range of the golfball? (Use g = 32 ft/sec2)
1) 60 ft
2) 375 ft
3) 600 ft
4) 690 ft
5) 720 ft
Answers to Exam #1
1. 1
2. 2
3. 5
4. 4
5. 3
6. 4
7. 4
8. 5
9. 5
10. 3
11. 5
12. 5
13. 4
14. 5
15. 3
16. 4
17. 2
18. 3
19. 4
20. 5
October 4, 1996
USEFUL INFORMATION
Acceleration of gravity = 10 m/sec2 = 32 ft/sec2
1 pound = 4.45 Newtons.
|
q
|
30°
|
37°
|
45°
|
53°
|
60°
|
|
sin q
|
0.5
|
0.6
|
0.707
|
0.8
|
0.866
|
|
cos q
|
0.866
|
0.8
|
0.707
|
0.6
|
0.5
|
|
tg q
|
0.58
|
0.75
|
1.0
|
1.33
|
1.73
|
1. A weight lifter weighs 256 pounds. What is his mass in slugs?
1) 6 slugs
2) 8 slugs
3) 12 slugs
4) 25.6 slugs
5) 256 slugs
2. A weight lifter weighs 256 pounds. What is his weight in Newtons?
1) 8 N
2) 25.6 N
3) 57.5 N
4) 1139.2 N
5) 2560 N
3. The mass of a baseball is 0.15 kg. If a force of 6000 N acts on it, what is its acceleration?
1) 187.5 m/sec2
2) 600 m/sec2
3) 900 m/sec2
4) 40,000 m/sec2
5) 60,000 m/sec2
4. Which statement about an accelerating object is TRUE?
1) The net force is not zero.
2) The momentum is constant.
3) The speed and direction of motion are constant.
4) The object is at rest.
5) The object is moving at constant velocity.
5. What force is required to accelerate a woman of mass 60 kg from rest to a speed of 8 m/sec in 2 seconds?
1) 4 N
2) 120 N
3) 240 N
4) 360 N
5) 480 N
6. A student weighs 160 lb. What is his mass, and what force is required to give him an acceleration of
6 ft/sec2?
1) m = 5 slugs; F = 30 lb
2) m = 5 slugs; F = 192 lb
3) m = 5 slugs; F = 960 lb
4) m = 16 slugs; F = 10 lb
5) m = 16 slugs; F = 96 lb
7. An object slides down a frictionless incline plane as shown. Which statement is FALSE?
1) The mass accelerates down the plane.
2) The acceleration is less than the
acceleration of gravity by a factor of sinq.
3) The normal force is mgcosq.
4) The net force on the mass is zero.
5) The acceleration of the object does not
depend on its mass.
8. A skier starts from rest and slides down a frictionless inclined plane as shown below. What is her acceleration down the incline, and what is the skier’s velocity after five seconds?
1) a = 6 m/sec2; v = 1.2 m/sec
2) a = 6 m/sec2; v = 30 m/sec
3) a = 8 m/sec2; v = 1.6 m/sec
4) a = 8 m/sec2; v = 40 m/sec
5) a = 10 m/sec2; v = 50 m/sec
9. What applied force is required to hold a 500 N weight on the frictionless incline shown below?
|
|
1) 300 N
2) 400 N
3) 500 N
4) 625 N
5) 833 N
10. A sled weighs 500 lb and rests on a level surface. If the coefficient of static friction is 0.8, and the coefficient of kinetic friction is 0.6, what force is required to just start the sled moving?
1) 15.625 lb
2) 300 lb
3) 400 lb
4) 500 lb
5) 625 lb
11. The mass of a refrigerator is 100 kg. The kinetic frictional force between the refrigerator and the floor is 200 N, and the refrigerator is pushed by a student with an applied force of 500 N as shown below. What are the net forces on the refrigerator and its’ acceleration?
1) Fnet = 300N; a= 0.3 m/sec2
2) Fnet = 300N; a= 3.0 m/sec2
3) Fnet = 700N; a= 0.7 m/sec2
4) Fnet = 700N; a= 7.0 m/sec2
5) Fnet = 1700N; a = 17 m/sec2
12. An object rests on an incline as shown below. Which statement is FALSE?
1) The acceleration of the mass is zero.
2) The net force on the mass is zero.
3) The component of the weight down the
incline is mgsinq,
4) The force of static friction is equal to
the object’s weight.
5) The normal force is mgcosq.
13. Which statement is FALSE?
1) The net force on an object moving with constant velocity must be zero.
2) If the net internal force on the system is zero, then the momentum of the system is conserved.
3) Speed is the rate at which distance is covered.
4) Acceleration is the rate at which velocity changes.
5) Force is the rate at which momentum changes.
14. A baseball (mass = 0.15 kg) is hit and travels at a velocity of 60 m/sec. It is caught by a person who exerts a force on the ball over a time of 0.02 seconds. What force is exerted by this person on the ball?
1) 0.4 N
2) 13.5 N
3) 135 N
4) 450 N
5) 3000 N
15. A hockey puck (mass = 0.2 kg) is initially at rest. If it is hit with a hockey stick which exerts a 300 N force for 0.04 seconds, what velocity will the puck attain?
1) 20 m/sec
2) 25 m/sec
3) 30 m/sec
4) 60 m/sec
5) 300 m/sec
16. A mom (M = 40 kg) and her son (m = 20 kg) go ice skating. The mom is at rest and the boy skates toward her with a speed of 9 m/sec. The boy collides with his mom and hugs her tight. After the collision the velocity of the mom/son combination is:
1) 3 m/sec
2) 4.5 m/sec
3) 6 m/sec
4) 9 m/sec
5) 12 m/sec
17. A mom (M = 40 kg) and her son (m = 20 kg) are standing at rest in the middle of a frictionless ice rink. The boy pushes his mom so that she moves away with a speed of 4 m/sec. What is the boy’s speed in the opposite direction?
1) zero
2) 1 m/sec
3) 6 m/sec
4) 8 m/sec
5) 12m /sec
18. The picture below shows a 4000 kg truck traveling to the right with a speed of 10 m/sec, and a 2000 kg car traveling to the left with a speed of 30 m/sec. The two collide and stick together. The velocity of the combination after the collision is:
1) zero.
2) to the right.
3) to the left.
19. The coefficient of restitution of a basketball on cement is 0.7. If a basketball is dropped from a height of
1 m, to what height will it rebound?
1) 0.35 m
2) 0.49 m
3) 0.57 m
4) 0.7 m
5) 1.43 m
20. A soccer ball traveling at 40 ft/sec collides with a person’s head traveling at 20 ft/sec as shown below. After the collision, the head rebounds back with a speed of 5 ft/sec and the ball rebounds back with a speed of 25 ft/sec. What are the velocity differences between the head and the ball before (u1 - u2) and after
(v1 - v2) the collision, and what is the coefficient of restitution (e)?
|
|
1) u1 - u2 = 20 ft/sec; v1 - v2 = 20; e= 1.0
2) u1 - u2 = 20 ft/se ; v1 - v2 = 30; e= 0.67
3) u1 - u2 = 60 ft/sec; v1 - v2 = 20; e= 0.33
4) u1 - u2 = 60 ft/sec; v1 -v2 = 30; e=0.5
5) u1 - u2 = 60 ft/sec; v1 - v2 = 30; e=2.0
Answers to Sample Exam #2
1. 2
2. 4
3. 4
4. 1
5. 3
6. 1
7. 4
8. 2
9. 1
10. 3
11. 2
12. 4
13. 2
14. 4
15. 4
16. 1
17. 4
18. 3
19. 2
20. 4
