Physics 7110 Midterm
1. A Mack truck and a Volkswagen  traveling at the same speed collide head-on. The impact force is greatest on the
a. Volkswagen b. Mack truck c. ...is the same for both

2. A Mack truck and a Volkswagen traveling at the same speed have a head-on collision. The vehicle to undergo the greatest change in velocity will be the
a. Volkswagen  c. both the same
b. Mack truck

3. A car traveling at 100 km/hr strikes a hapless bug and splatters it. The force of impact is greater on the
a. bug    c. ... is the same for both
b. car

4. A horse exerts 500 N of force on a heavy wagon. The wagon pulls back on the horse with an equal force. The wagon still accelerates because
a. these forces are not an action-reaction pair
b. nevertheless there is still an unbalanced force on the wagon
c. the horse pulls on the wagon a brief time before the wagon reacts
d. ...the wagon does not accelerate because these forces are equal and opposite
e. none of these

5. A rifle of mass 2 kg is suspended by strings. The rifle fires a bullet of mass 1/100 kilogram at a speed of 200 m/s. What is the recoil velocity of the rifle?
a. 0.001 m/s   d. 1 m/s
b. 0.01 m/s   e. none of these
c. 0.1 m/s

6. A boxcar rolling free along a side track at 2 m/s strikes and couples with another boxcar of equal mass. The speed of the two boxcars moving together immediately after the collision is
a. 2 m/s
b. 1 m/s
c. less than 1 m/s
d. can't be determine without data on the energy lost.

7. A projectile is fired at  a tall piece of wood. Assuming that impact times are the same, the impact force on the block is greatest when
a. the projectile goes through the block
b. the projectile is stopped by the block
d. the projectile bounces back from the block.

8. An object that has potential energy has this energy because of its
a. speed   d. location
b. acceleration  e. none of these
c. momentum
9. Two objects, A and B, have the same size and shape but A is twice as heavy as B. When they are dropped simultaneously from a tower, they reach the ground at the  same time (neglecting friction), but A has a higher
a. speed   d. all of the above
b. acceleration  e. none of the above
c. momentum

10. Bullets are fired from an airplane in the forward direction of motion. The momentum of the airplane will be
a. decreased   c. increased
b. unchanged

11. An object at rest may have
a. speed   d. momentum
b. velocity   e. none of these
c. energy

12. A 400 N woman stands on top of a very tall ladder so she is one Earth radius above the Earth's surface. How much does she weigh?
a.zero    d. 400 N
b. 100 N   e. none of these
b. 200 N

13. On a meter stick which is balanced at its center, a 100 gm mass is hung at a distance 10 cm from the center and another 100 gm mass is hung 20 cm from the center on the same side. The system will balance if a 200 gram mass is hung on the other side of the center at a distance from the center of
a. 10 cm
b. 15 cm
d. 20 cm
e. 30 cm

14. When the distance between two stars decreases to half, the force between them
a. decreases to one quarter
b. decreases to one half
c. doubles
e. none of the above

15. When a bullet is fired from a rifle, the force on the rifle is equal to the force on the bullet. However, the kinetic energy of the bullet is greater than the kinetic energy of the recoiling rifle because the
a. force on the bullet acts for a longer distance
b. bullet's momentum is greater than that of the rifle
c. force on the bullet acts for a longer time
d. bullet velocity is greater and kinetic energy depends more strongly on velocity
e. none of these

16. If the Earth's mass decreased to one-half its original mass with no change in radius, then your weight would
a. decrease to one quarter of your original weight
b. decrease to one half of your original weight
c. stay the same
d. none of these

17. A popular swinging-balls apparatus consists of an aligned row of identical elastic balls that are suspended by strings so they barely touch each other. When two balls are lifted from one end and released, they strike the row and two balls pop out from the other end. If instead one ball popped out with twice the velocity of the two, this would be a violation of the principle of conservation of
a. momentum  c. both of the above
b. energy   d. none of the above

18. A car accelerates at 2 meters per second squared. What is its speed 3 seconds after the car starts moving?
a. 2 m/s   d. 6 m/s
b. 3 m/s   e. none of these
c. 4 m/s

19. When a rock thrown straight upward gets to the exact top of its path, its
a. velocity is zero and its acceleration is zero.
b. velocity is zero and its acceleration is about 10 meters per second squared.
c.velocity is about 10 m/s and its acceleration is zero.
d. velocity is about 10 m/s and its acceleration is about 10 meters per second squared.
e. none of these.

20. A bullet is dropped from the top of the Empire State Building while another bullet is fired downward from the same place. After the bullet has left the gun, neglecting air resistance, acceleration is greatest for the
a. fired bullet
b. dropped bullet
c. ... is 9.8 m/s2 for each
d. depends on how far they are above the earth.

21. Someone standing at the edge of a cliff throws one ball straight up and another ball straight down at the same initial speed. Neglecting air resistance, the ball to hit the ground  below the cliff with the greatest speed will be the one initially thrown
a. upward.   c. ... they will both hit
b. downward     with the same speed.

22. The impact force of a rock falling to the ground from a height of 10 meters
a. is determined entirely by its mass and original height
b. is determined entirely by its mass and the velocity with which it hits
d. cannot be determined without knowing how far the rock traveled after impact.

23. If a car travels further during a collision (i.e., collapses more)
a. more work will be done on it.
b. the change in kinetic energy will be greater
c. the change in momentum will be less
d. the average force of impact will be less

24. A net force of 50 newtons acts on a 2 kg block and moves it 4 meters in the direction of the force. The work done on the block is
a. 100 joules
b. 200 joules
c. 400 joules
d. 1000 joules

25. A satellite near the Earth makes a full circle in about an hour and a half. How long would a satellite located as far away as the Moon take to orbit the earth?
b. about an hour and a half
c. it depends on the mass of the satellite
d. a satellite could not be put in such an orbit.
e.none of these

26. If you have to stop quickly on the expressway,
a. you always get a shorter stopping distance if your wheels are rolling rather than locked.
b. you get a shorter distance if your wheels are locked rather than rolling.
c. you get a shorter stopping distance with wheels rolling provided you are very near the maximum static friction force.

27. A sack of potatoes weighing 200 N falls from an airplane. As the velocity of fall increases, air resistance also increases. When air resistance equals 200 N, what is the sack's acceleration?
a. 0   d. infinite
b. 4.9 m/s2  e. none of these
c. 9.8

28. A bullet fired horizontally hits the ground in 0.5 seconds. If it had been fired with a much higher speed in the same direction, it would have hit the ground (neglecting the earth's curvature and air resistance ) in
a. less than 0.5 sec  c. 0.5 seconds.
b. more than 0.5 sec

29. If a car traveling at 20 meters/s is stopped by friction in a distance d, then a car traveling at 40 m/s would require a stopping distance of about
a. d
b. square root of 2 times d
c. 2d
d. 4d

30. An object is placed halfway between the Earth and Moon. The object will fall toward the
a. Moon  c. neither of these
b. Earth

31. A woman on the surface of the Earth has a mass of 50 kilograms and a weight of 490 newtons. If the woman were floating freely inside a space habitat far away from Earth, she would have
a. less weight and more mass
b. less weight and the same mass.
c. less weight and less mass
d. more weight and less mass.
e. none of these.

32. A man falling through the air with a parachute weighs 500 N. When he opens his chute, he experiences and initial air resistance force of 800 N. The net force on the man is at that time is
a. 300 N downward  d. 300 N upward
b. 500 N downward  e. 500 N upward
c. 800 N upward

33. A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly. The reason this can be done is that
a. the milk carton has no acceleration.
b. there is an action-reaction pair operating.
c. the gravitational field pulls on the milk carton.
d. the milk carton has inertia
e. none of these

34. Compared to its mass on the Earth, the mass of an object on the Moon is
a. less
b. more
c. the same

35. Suppose an object's mass is decreasing. If a constant force is applied to the object, the acceleration
a. decreases    c. remains the same
b. increases

36. A car traveling at  40 km/hr around a particular curve requires a frictional force on the tires of 400 newtons to keep the car in the circular path. If the car rounded the same curve at 80 km/hr, the sideways force required from the road would be
a. 400 N
b. 200 N
c. 800 N
d. 1600 N

37. The force of friction on a sliding object is 10 Newtons. The force needed to maintain a constant velocity is
a. more than 10 N  c. 10 N
b. less than 10 N

38. An apple weighs 1 N. The net force on the apple when it is in free fall is
a. 0 N   d. 9.8 N
b. 0.1 N  e. none of these
c. 1 N

39. A tow truck exerts a force of 3000 N on a car, accelerating it at 2 m/s2. What is the mass of the car?
a. 500 kg  d. 3000 kg
b. 1000 kg  e. none of these
c. 1500 kg

40. A bag of groceries has a mass of 10 kg and a weight of about
a. 1 N   d. 1000 N
b. 10 N  e. none of these
c. 100 N

41. An object following a straight-line path at constant speed
a. has a net force acting upon it in the direction of motion
b. has zero acceleration
c. must be moving in a vacuum
d. has no forces acting on it
e. none of the above

42. Neglecting air friction and lift, the "hang time" of a punted football would depend upon
a. the initial vertical velocity only
b. the initial horizontal velocity only
c. both the initial vertical and horizontal  velocity.

43. A hockey puck is set in motion across a frozen pond. If ice friction and air resistance are neglected, the force required to keep the puck sliding at constant velocity is
a. zero newtons
b. equal to the weight of the puck
c. the weight of the puck divided by the mass of the puck
d. the mass of the puck multiplied by 9.8 m/s2.
e. none of these

44. A 10 N block and a 1 N block lie on a horizontal frictionless table. To push them with equal acceleration, we would have to push with
a. equal forces on each block
b. ten times as much force on the heavier block
c. ten squared or 100 times as much force on the heavier block
d. one tenth as much force on the heavier block
e. none of the above

45. Suppose a particle is accelerated through space by a 10 N force. Suddenly the particle encounters a second force of 10 N in the opposite direction of the first force. The particle
a. is brought rapidly to a halt.
b. decelerates gradually to a halt
c. continues at the speed it had when it encountered the second force.
d. theoretically accelerates to speeds approaching the speed of light in the absence of a net force
e. none of these.

46. In which case would you have the largest mass of gold? If your chunk of gold weighed 1 N on the
a. Moon  c. planet Jupiter
b. Earth

47. A player catches a ball. Consider the action force to be the impact of the ball against the player's glove. What is the reaction pair force to this force?
a. the player's force on the glove
b. the force the glove exerts on the ball
c. friction of the ground against the player's shoes
d. the muscular effort of the player's arms
e. none of these

48. A car traveling at 22 m/s hits a tree and comes to a stop. The driver's seatbelt minimizes the force on the driver by
a. making the drivers stopping distance shorter than that of the car
b. reducing the work that must be done to stop the driver
c. making the driver's stopping distance equal to or greater than the stopping distance of the car.
d. reducing the impulse on the driver.

49. A person is attracted toward the center of the earth by a 500 N gravitational force. The force with which the earth is attracted toward the person is
a. very very small  c. 500 N
b. very very large

50. In order to catch a ball, a baseball player moves his or her hand backward in the direction of the ball's motion. Doing this reduces the force of impact on the players hand principally because
a. the resultant velocity of impact is lessened
b. the momentum of impact is reduced
c. the time of impact is increased
d.  the time of impact is decreased
e. none of these

51. A car traveling along the highway needs a certain amount of force exerted on it to stop in a given distance. More stopping force may be required when the car has
a. more mass   d. all of the above
b. more momentum  e. none of the above
c. higher velocity

52. The force on an apple hitting the ground depends upon
a. whether or not the apple bounces
b. the speed of the apple just before it hits
c. the time of impact with the ground
d. the distance the apple moves after impact
e. all of these
f. none of these

53. When you jump from an elevated position you usually bend your knees upon reaching the ground. By doing this, the distance traveled during  the impact is about 10 times more than it would be in a stiff-legged landing. In this way the average force your body experiences is reduced by
a. less that 10 times  c. about 10 times
b. more than 10 times

54. A ball is launched straight upward with an initial  speed of  20 m/s. Assuming a value of 10 m/s2 for the acceleration of gravity, it will reach the top of its motion in
a. 1 second
b. 2 seconds
c. 3 seconds
d. 4 seconds
It will  reach a maximum height of
a. 10 m
b. 20 m
c. 30 m
d. 40 m

55. A karate expert executes a swift blow and severs a cement block with her or his hand. The
a. impulse on both the block and the expert's hand have the same magnitude
b. force on both the block and the expert's hand have the same magnitude
c. time of impact on both the block and the expert's hand have the same magnitude
d. all of the above
e. none of the above

56. As an object freely falls, its
a. velocity increases
b. acceleration increases.
c. both of the above
d. none of the above

57. If an object  falls with constant acceleration, the velocity of the object must
a. be constant also
b. continually change by the same amount each second.
c. continually change by varying amounts depending on its speed at any point.
d. continually decrease
e. none of these

58. A ball is thrown upwards and caught when it comes back down. Neglecting air resistance, the speed with which it is caught is
a. more than the speed it had when thrown upwards.
b. less than the speed it had when thrown upwards.
c. the same as the speed it had when thrown upwards.

59. In a karate blow to a board, assuming the same speed of the hand just before the blow, the maximum force to the hand will occur if
a. the board breaks and the hand continues past the point of contact
b. the board exactly stops the hand
c. the hand bounces back from the board without breaking it

60. A car travels in a circle with constant speed. the net force on the car
a. is directed forward, in the direction of travel
b. is zero because the car is traveling with constant speed
c. is directed toward the center of the circle
d. none of these

61. A 1 kg chunk of putty moving at  1 m/s collides and sticks to a 5 kg bowling ball that is initially at rest. The bowling ball with its putty passenger is then set in motion with a momentum of
a. 0 kg m/s   d. 5 kg m/s
b. 1 kg m/s    e. none of these
c. 6 kg m/s

62. If the polar ice caps melted, the resulting water would spread over the entire Earth. This new mass distribution would tend to make the length of day
a. longer   c. stay the same
b. shorter

63. Suppose an astronaut in outer space wishes to play a solitary 'throw, bounce, and catch' game by tossing a ball against a very massive and perfect elastic concrete wall. If the ball is as massive as the astronaut
a. the astronaut will catch one bounce only.
b. the astronaut's time between catches will decrease as the game progresses.
c. the astronaut will never catch the first bounce
d. none of these

64. The reason the Moon does not fall into the Earth is that
a. the Earth's gravitational field is weak at the moon.
b. the gravitational pull of other planets keeps the Moon up
c. the Moon has a sufficiently large orbital speed
d. the Moon has less mass than the Earth
e. none of these

65. What makes a chemical element distinct?
a. the number of protons
b. the number of neutrons
c. the number of electrons
d. the total mass of all the particles
e. none of these

66. Which potatoes when peeled produce the most peelings?
a. 10 kg of large potatoes
b. 10 kg of small potatoes
c. they both produce the same amount.

67. A box of weight 100 newtons is lifted to a height of 5 meters above the floor. If it is released from rest and falls toward the floor, the kinetic energy it has just before it hits the floor is
a. 100 newtons
b. 100 joules
c. 500 joules
d. 50 joules