Practice and Review-Newton’s laws of Motion Name ______Date ______
1. Draw a quantitative force diagram for the Atwood apparatus with a
4 kg cart being pulled by a 1 kg tower:
what is the acceleration of the cart? ______
b. Draw a quantitative force diagram for a a2 kg rock
(with negligible air resistance) that is thrown at 20 m/s straight up
and has reached half way to the top of its path.
What is the acceleration of the rock? ______
2. a. Arnold Strongman and Suzie Small pull on opposite ends of a rope in a tug of war. Who exerts the greatest force exerted on the rope (assume the rope’s mass is negligible)? ______
Explain:
b. Why does Arnold win the tug of war?
3. a. If a Mack truck and a Volkswagen beetle have a head on collision, which vehicle will experience the greater impact force? ______
Explain:
b. According to Newton’s 2nd Law, which vehicle in the collision will decelerate more? ______Explain:
4. a. Consider a 500 gram apple at rest in the palm of
Nellie Newton’s hand. What are all the forces acting on it?
Draw a force diagram with the magnitudes of the forces labeled.
b. If we call the gravitational force exerted on the apple the action, what is the reaction force according to
Newton’s 3rd Law? ______
c. Since the apple is at rest, net force on the apple is ______.
d. Since the perpendicular force is equal and opposite the apple’s weight can we say that these two forces comprise an action-reaction pair?
Explain
e. If we say that the action force is the earth pulling down on the apple, what is the reaction force?
f. Do the perpendicular force of the hand on the apple and the apples weight comprise an action-reaction pair?
g. Another pair of forces is the perpendicular force of the palm on the apple and the downward force of the apple against Nellie’s hand. Is this force pair an action-reaction pair?
h. Suppose Nellie now pushes upward on the apple with a force of 2 N. Is the apple in equilibrium? ______
Does the apple accelerate upward? ______. Compared to its weight, the magnitude of the perpendicular force is (choose one and circle)
the same, twice, not the same and not twice.
i. Once the apple leaves Nellie’s hand, the perpendicular force is (choose one and circle)
zero, twice the magnitude of the apples weight.
j. Once the apple leaves Nellie’s hand, the net force on the apple is (circle one)
zero only its weight
Part 3. For each diagram identify the action-reaction force pairs you see.
a. b.
.
c. d.