1. Midterm exam Review

2. When an object is in free fall….
a. It always has an acceleration of 10 m/s2 downward
b. It is travelling a greater distance each successive second
c.Its velocity is changing by -10 m/s every second
d. It is not under the influence of anything except gravity
e. all of the above.

3. ____A car starts from rest and after 7 seconds it is moving at 42 m/s
____A car starts from rest and after 7 seconds it is moving at 42 m/s. What is the car’s average acceleration?
a m/s2 b m/s2 c. 6 m/s2
d m/s e. none of these

4. A ball is thrown upwards with a velocity of 40 m/s and caught when it comes back down. If there is no air resistance, the velocity of the ball at its highest point would be
a. 10 m/s b. 10 m/s2 c. 0 m/s d m/s e m/s

5. If a skydiver jumps out of a plane he will eventually stop accelerating (before the parachute is opened), This happens because….
a. He keeps the same speed as he jumped out of the plane with the entire time he’s falling
b. The skydiver will keep on accelerating until the parachute is opened or he hits the ground
c. The air resistance will eventually become so strong that gravity no longer accelerates him, and he reaches terminal velocity
d. Because terminal velocity is reached once the skydiver is travelling at the speed of sound

6. ___Suppose a jumper claims a hang time of 2 seconds when jumping straight up. Then that jumper must be able to leave the ground with a speed of
a m/s.
b. 5 m/s.
c m/s.
d m/s.
e m/s.

7. Suppose a small plane can fly at 170 km/h relative to the surrounding air. Suppose also that there is a 60 km/h headwind (a wind blowing in the opposite direction as the plane is flying). How fast does an observer on the ground see the plane go?
a.110 km/h
b km/h
c km/h
d km/h
e km/h

8. A 10 kg object is accelerated from rest to a speed of 4 m/s, how much work was done on the object?
a J
b. 40 J
c J
d J

9. What is the equation for Momentum?

10. According to Newton’s 2nd Law What is the relationship between mass and acceleration?

11. ____ A ball tossed vertically upward rises, reaches its highest point, and then falls back to its starting point. During this time the acceleration of the ball is always
a. in the direction of motion.
b. directed upward.
c. opposite its velocity.
d. directed downward.

12. ____The reason padded dashboards are used in cars is that they
a.increase the force of impact in a collision.
b.decrease the momentum of a collision.
c.increase the time of impact in a collision.
d.look nice and feel good.
e.decrease the impulse in a collision.

13. ____ Superman and a very massive asteroid are both at rest in space, if superman throws the asteroid, which of the two objects will most faster, Superman or the asteroid?
a. They both move at the same speed.
b. The asteroid
c. Superman

14. A 4.0-kg ball has a momentum of 20.0 kg·m/s. What is the ball's speed?
a m/s
b m/s
c m/s
d m/s
e. none of the above

15. The change in momentum of an object is equal to the
a. velocity change of the object.
b. object's mass times the force acting on it.
c. force acting on it times its velocity.
d. force acting on it.
e. impulse acting on it.

16. ____ Compared to a sports car moving at 30 miles per hour, the same sports car moving at 60 miles per hour has
a. four times as much momentum.
b. twice as much momentum.
c. the same momentum.

17. a. 2 kg m/s b. 4 kg m/s c. 3 kg m/s d. 0 kg m/s
If a 1 kg glider moving at 2 m/s collides inelastically with another glider of the same mass that was initially at rest
____ What was the initial momentum of the entire system (both carts)
a. 2 kg m/s b. 4 kg m/s c kg m/s d kg m/s
____ What is the final momentum of the entire system (both carts)?
____ What is the velocity of the two combined carts after the collision?
a. 0 m/s b. 1 m/s c m/s d. 2 m/s
1 kg
2 m/s

18. True/False
Indicate whether the sentence or statement is true or false.
____ 27. Impulse is defined as the force exerted on an object times the time it lasts.
____ 28. When a baseball player follows through in hitting the ball, the contact time with the ball is longer.
____ 29. When two objects collide and stick together, the collision is said to be inelastic.
____ If a net force acts on a system, the system's momentum will change.
_____ 33. Impulse is equal to the change in momentum

19. The mass of a sheep that weighs 110 N is about
a kg.
b kg.
c kg.
d kg.
e. none of the above

20. The center of gravity of a human body is located at a point
a. that can change depending on how the body is oriented.
b. that is always directly behind the belly button, no matter how the body is oriented
c. that is fixed no matter what.
d none of the above

21. ___Earth pulls on the moon, and similarly the moon pulls on Earth
___Earth pulls on the moon, and similarly the moon pulls on Earth. This is evidence that the a.
Earth's and moon's pulls comprise an action-reaction pair.
b.Earth and moon are simply pulling on each other.
c.both a and b
d.neither a or b

22. Two gliders having the same mass and the same speed move toward each other on an air track and stick together. After the collision, the velocity of the gliders is
a. There is not enough information to say.
b. the same as the original velocity.
c. zero.
d. one half the original velocity.
e. twice the original velocity.

23. ____ 28. A ball is thrown directly upward at a speed of 30 m/s, how long will it take to reach its highest point?
A ball is thrown directly upward at a speed of 30 m/s, how long will it take to reach its highest point?
a. 1 sec
c. 4 sec
b sec
d. 6 sec

24. An object thrown into the air with a spin rotates about its
a. geometric center.
b. center of gravity.
c. edge.
d. none of the above
e. midpoint.

25. In an elevator that is accelerating in the downward direction, you will feel as if you weigh ______ but in actuality you will weigh ____________.
a. Less, more
b. More, less
c. The same, more d. less, the same

26. ____ 11. When you release the open end of a balloon the balloon will fly across the room, which of Newton’s Laws best explains this? a.
1st Law b. 2nd Law c. 3rd Law

27. A 5-N force and a 30-N force act in the same direction on a 7 kg object. What is the acceleration of the object?
a.35 m/s2
b. 5 m/s2
c. 7 m/s2
d m/s2

28. A tennis ball and a bowling ball are dropped at the same time
A tennis ball and a bowling ball are dropped at the same time. Which ball has the greater gravitational force acting on it?
a. The bowling ball
b. The tennis ball
c. They both have the same force acting on them.

29. Once a satellite is put into orbit in outer space it will stay in orbit forever moving at a constant speed without engines ever firing, which of Newton’s Laws accounts for this?
a. 1st Law b. 2nd Law c. 3rd Law

30. ____ True/False
Indicate whether the sentence or statement is true or false.
____ 33. Friction refers to the force between two surfaces that are sliding past each other.
____ 34. If a hockey puck were to slide on a perfectly frictionless surface, it will eventually slow down because of its inertia.
____ 35. The acceleration of an object is inversely proportional to the net force acting on it.
____ How heavy you ‘feel’ depends on the normal force acting on you, not your actual weight.
____ If you were riding in a car that was moving at a constant velocity and threw a baseball straight up, it would land in the back of the car.
____ 38. The force due to gravity acting on an object is also referred to as its mass.
____ 39. Whenever one object exerts a force on another object, the second object always exerts a force back on the first object.

31. If a rider in a car does not have her seatbelt on and the car get into a head on collision the rider will likely be thrown forward through the windshield, this is an example of Newton’s _____ Law.
1st b. 2nd c. 3rd d. 4th

32. ____ A vector is a quantity that has
a. magnitude and time b. time and direction c magnitude and direction

33. _____5. The horizontal component of a projectile's velocity is never affected by
a. a horizontal wind
b. gravity
c. the vertical component of its velocity d. b & c

34. In the absence of air resistance, the angle at which a thrown ball will go the farthest is
a. 15⁰ b. 30⁰ c. 45⁰ d. 60⁰ e. 75⁰

35. A baseball is hurled into the air at an angle of 30 degrees above the horizontal and lands on a target that is at the same level as that where the baseball started. The baseball will also land on the target if it is thrown at an angle of
a. 20⁰ b. 40⁰ c. 50⁰ d. 60⁰ e. none of the above

36. Suppose a small plane can fly at 170 km/h in the North direction
Suppose a small plane can fly at 170 km/h in the North direction. Suppose also that there is a 60 km/h Northern wind. What is the plane’s resultant velocity?
5 km/h b. 60 km/h c km/h d.170 km/h e. 230 km/h

37. What is the resultant of the two vectors 75 km East & 25 km West?
100 km East b km West c km East d km West e.25 km West

38. City B is directly East of City A
City B is directly East of City A. If a plane wishes to travel from City A to City B while there is a strong wind that is directed North, in which direction should the plane direct itself so that it winds up in City B? A B

39. A projectile is launched upward at some angle
A projectile is launched upward at some angle. If it takes 6 seconds to reach its highest point, what was its initial vertical velocity?

40. A bomber plane, flying at a high speed, is planning to drop a bomb onto a city, in order to hit the city when should the bomber release the bomb.
a. Before it reaches the city
b. after it passes the city
c. when its directly above the city

41. True/False Indicate whether the sentence or statement is true or false.
____ 22. Mass is a vector quantity.
____ 23. A single vector can be replaced by two vectors in the x- and y-directions that are at right angles to each other.
____ If a ball is thrown at an angle of 70 degrees, it’s x-component of velocity is larger than its y-component of velocity.
____ 25. Speed is a vector quantity.
____ An object thrown at an angle of 20˚ will have a longer hang-time than an object thrown at 60˚.

42. A brick has a weight of 10 N, if this brick is at rest in your hands what is the net force on it?

43. A projectile launched with a speed of 30 m/s at an angle of 70° will…
a. will initially be moving faster horizontally than it is vertically
b. will initially be moving faster vertically than it is horizontally
c. will initially be moving equally as fast horizontally as it is vertically
d. all of the above
70°

44. If you swing a baseball bat, which part of the bat has the fastest linear speed..
A) the end of the bat
B) the handle of the bat
C) the middle of the bat
D) all parts of the bat have the same linear speed

45. If you swing a baseball bat, which part of the bat has the fastest rotational speed..
A) the end of the bat
B) the handle of the bat
C) the middle of the bat
D) all parts of the bat have the same linear speed

46. **Not on 2013 TEST** If the dot on the below picture represents the Center of Gravity of the block, will it topple or stay upright?

47. When you punch a wall, which of the following values are larger compared to when you punch a pillow?
A) change in momentum
B) Impulse
C) Change in speed
D) Force
E) all of the above

48. A car goes from being at rest to a speed of 30 m/s in 6 seconds, what is the cars acceleration?

49. Which is more “elastic”, a tennis ball or a billiard ball?

50. A calorie is a unit for what type of quantity?

51. ____ Which path below would best represent the path of a bomb that’s being dropped from a moving airplane as an observer from ground would see it (no air resistance)?

52. What is the net force on an object that is moving at a constant velocity of 30 m/s?

53. What unit is mass measured in?

54. What unit is weight measured in?

55. What would the result of an INELASTIC collision look like?

56. Can two different people observe the same object to be going at two different speeds at the same time?

57. A projectile is shot straight upwards at 40 m/s, how long will it take the projectile to return to the point it was fired from?

58. Pushing a heavy object up a ramp instead of directly lifting it will do which of the following?
A) Reduce the amount of work you have to do
B) Reduce the amount of force you have to apply
C) Reduce the distance a force has to be applied over
D) All of these

59. If you are pulling a cart will a force of 20 N and the cart rolls at a constant velocity….
A) How much is the net force on the cart?
B) how much is force of friction on the cart?

60. Simple machines do which of the following?
A) multiply work
B) multiply force
C) multiply energy
D) multiply momentum
E) all of the above

61. What makes a boat in seas like this more likely to roll to one side?

62. Are satellites projectiles?

63. What is the name for the sum or combination of vectors?

64. Newton’s 3rd law states that every force has an equal and opposite reaction force, if we call the force of the Earth’s gravity pulling you downward the ‘action’ force… what is the ‘reaction’ force to this?

65. While hitting a homerun, a baseball is hit by a bat… which object experiences the greater force during the collision?
Triceps Day!!

66. In which of these situations is work being done?
A) You are holding a boulder
B) You are lifting a boulder from the ground to above your head
C) A ball is rolling at a constant velocity across a frictionless surface

67. A 5 kg backpack is carried to the top of a 20 m high hill, how much work was done on the backpack?

68. Two cars drive toward each other on the highway, according to a stationary observer car 1 is moving at 60 mph East and car 2 is moving at 70 mph West. What is the velocity of Car 1 relative to Car 2?
a mph West
b mph West
c mph
d mph East

69. A baseball is thrown straight up into the air, halfway through its trajectory, at the top of its path the net force on the baseball is equal to….
A) 0 N
B) its weight
C) its mass
D) cannot be known

70. Name three different ways in which you could be “accelerating”?

71. True or False
As a projectile flies through the air the horizontal component of its velocity is changing.

72. While using a lever, the short end moves a distance of 7 cm and the long is pushed a distance of 42 cm. What is the mechanical advantage of the lever?
a. 1/6
b. 10
c. 6
d. 7

73. When an objects speed triples by what factor will its kinetic energy change?