Newton’s Laws Review Sheet

Newton’s 1st Law = objects at rest will ______, objects in motion will ______, unless acted on by a ______.

  1. What property do objects have that makes them want to keep moving at CV in a straight line? ______
  1. 3 ways an object canaccelerate: ______, ______, ______
  1. In a car accident, the seat belt’s job is to:______

a. cancel out the forces on the person

b. provide a net force backwards on the person

c. provide a net force forwards on the person

d. balance the forces on the person

  1. The headrest’s job is to:______

a. cancel out the forces on the person

b. provide a net force backwards on the person

c. provide a net force forwards on the person

d. balance the forces on the person

  1. If the forces acting on something are not balanced (net force), the object is ______.
  1. If all of the forces on it are balanced, it is either ______or moving at a ______.

Newton’s 2nd Lawa = ΣF/mFg = mg

  1. Two people are pulling on a lawmower. Tom is pulling with 500N to the left, and Jim-Bob is pulling with 850N to the right.
  2. What is the net (unbalanced) force on the mower?
  1. If the mower has a mass of 75kg, what its acceleration?
  1. An elephant weighs 8000 N on earth. (g earth = 9.8)
  2. What is its mass?
  1. What is its weight (in N) on the moon?(g moon = 1.6)
  1. A pilot (mass = 65 kg) is doing maneuvers in his jet.
  2. What is the pilot’s weight in N?
  1. When he is accelerating up does he feel light, heavy, weightless or normal?
  2. When he is moving at CV up does he feel light, heavy, weightless or normal?
  3. When he is accelerating down does he feel light, heavy, weightless or normal?
  4. If his engines cut out, and his plane freefalls, does he feel light, heavy, weightless or normal?

Newton’s 3rd Law = every action has a(n) ______

  1. In a football tackle, who exerts the bigger force on the other: the tackler, the guy getting tackled, or are the forces the same?
  2. What if the tackler has three times the mass of the other guy?
  3. What if the tackler is running really fast when he tackles the other guy?
  4. The winner of a tug-of-war is the one who ______
  5. Pulls the hardest on the rope
  6. Gets the best friction with the floor
  7. Makes the meanest face
  8. Has the biggest muscles
  1. A tennis ball is dropped, and it goes into freefall. What is the correct action-reaction pair for this?
  2. Earth pulls the ball down, and air pushes it back up
  3. The ground pulls the ball down, and air pushes it back up
  4. Earth pulls the ball down, the ball pulls the Earth up
  5. Trick question - there is no reaction force for gravity

15. When two things collide, the forces on both objects are always the same, but their ______are different, assuming they have different masses.

Friction

16. The two types of friction are:

  • ______which resists starting sliding
  • ______which resists continued sliding
  • Which type of friction is stonger?

17. Mr. S is pushing on a heavy cart trying to get it to slide.

(choices: move, won’t move)

  • If his applied force is less than the static maximum, the cart will ______
  • If his applied force is equal to the static maximum, the cart will ______
  • If his applied force is greater than the static maximum, the cart will ______

18. Mr S finally got the cart to start moving. While it is moving,

(choices: move at CV, speed up, slow down)

  • If his applied force is less than kinetic friction, the cart will ______.
  • If his applied force is equal to kinetic friction, the cart will ______.
  • If his applied force is greater than kinetic friction, the cart will ______.

19. Tony is pushing a football sled (mass = 120 kg) at a constant velocity, using an applied force of 815N. What is the coefficient of friction between the football sled and the grass field?

Free Response:

20.Assuming you had Star Trek technology, where could you go to instantaneously change your….

a) mass (but not your weight)?

b) true weight? (but not mass)

c) apparent weight? (but not mass)

21. Can you be weightless? How?

22. Can you be massless? How?

23. Fill in the chart with the definitions and their units.

Symbol / Definition / Units
m
Fg
Fn
g
a
µ

a) Bob is standing still on the floor.

b) Bob is riding in an elevator that is accelerating up.

c) Bob is riding in an elevator moving at CV up.

d) Bob is riding in an elevator that is accelerating down.

e) Tim is pushing a crate to the right and moving it at CV.

f )Tim is pushing on a crate to the right, and it is speeding up.

g) Tim pushes the crate off of a cliff, and it’s in freefall.