Physics- Newton’s Laws Test Review
Name:
1. What are the differences between mass and weight in terms of definition, how they are measured,
how (or if) they change in different locations in the universe, units of each.
2. You take a bowling ball and shake it back and forth. Is this significantly harder if you try this
experiment on the moon (or in deep space) compared to the Earth? Suppose the bowling ball is
dropped onto your big toe. Does this hurt you more if you were standing on the Earth or the moon?
Which example is this best explained by the mass of the ball vs the weight of the bowling ball?
Explain.
3. Many things can be inferred from the equation F=ma. Describe the relationship between the
following quantities as well as the quantity which is being kept constant in each case.
a. Between Force and Acceleration?
b. Between Mass and Acceleration?
c. Between Force and Mass?
4. Sketch the graph of each of these relationships.
F
a
F
a
m
m
5. A 400kg jet-ski is racing along at a steady 25mph due east.
A. Draw and label the forces on the jet-ski, considering a resistance force of 2000N.
B. Are these forces balanced or unbalanced? Explain how you
know.
6. A 400kg sled is being pulled by a pack of dogs over packed snow. At first the sled is at rest and the
coefficients of static and kinetic friction are given; μs=0.1, μk=0.06. Draw a fbd for each situation
A. Find the force to just get the sled to move.
B. Find the force applied by the dogs to accelerate
the sled from 1m/s to 7m/s in 2 seconds.
C. Find the force applied by the dogs to keep the
sled moving at 7m/s for one minute.
D. While the sled is moving 7m/s, the rope breaks
between the dogs and the sled. How far will the
sled travel as it comes to rest.
7. A skateboarder is going on a level road at 12m/s when the skateboard hits a curb that the
skateboarder did not see. Describe the skateboarder’s forward motion from the time just after the
skateboard hits the curb until the skateboarder lies motionless (and embarrassed).
Use Newton’s 1st and/or 2nd Laws to explain
8. Janet is mowing the lawn using a powered push mower. The handle is fixed and is at the angle
shown and the mower has a mass of 85 kg. If there is no friction and Janet pushes directly along the
handle with a magnitude of 120 N, what will be the net acceleration of the mower?
430
9. Look at the following vel vs time graph as a π kg box (get it, a pie-box, peach pie, my favorite) at
rest was pushed towards the motion detector. Describe the motion for the 4 sections of the graph.
Find the accel of the box as it comes to a stop, the frictional force (is this static or kinetic?) and μ.
10. A cart is sitting on a flat friction present horizontal table. A massless string is attached to the cart
and runs over a pulley to a mass hanging below the table. The cart has a mass of 16 kg and the
hanging mass has a mass of 9.0 kg. The coefficient of static friction is 0.45.
a. Will the hanging mass cause the cart to accelerate?
b. If the cart will accelerate, find the net acceleration of the system if the coefficient of kinetic
friction is 0.25.
11. Janet is looking to cause her weight to drop. She currently sits on top of a scale on the floor of an elevator.
Janet has a weight of 98N. Determine the Normal force necessary for her to ‘weight’ 20% less.