Physics

Ch 3 – Newton’s First Law

Pre-Test

1.  Which of these statements is true regarding inertia?

  1. Inertia is a force which keeps stationary objects at rest
  2. Inertia is a force that brings moving objects to rest
  3. An object would not have inertia in a gravity free environment (if such a place existed)
  4. All objects have inertia

2.  All of the following statements are true EXCEPT…

  1. Fast moving objects have more inertia than slow moving objects
  2. A person with a lot of inertia will have a more difficult time changing directions than a person with less inertia
  3. Mass and inertia are synonymous
  4. An objects inertia on the moon is identical to its inertia on Earth

3.  The amount of force required to keep an object moving at a constant speed in a frictionless environment is

  1. Equal to the mass of the object
  2. Equal to the weight of the object
  3. Zero
  4. Any amount greater than zero

4.  An object traveling in a straight line at constant speed must

  1. Have a non zero net force acting on it in the direction of motion
  2. Have zero net force acting on it
  3. Have no forces acting on it
  4. Be moving in a vacuum (completely empty space)

5.  A smooth table cloth can be quickly pulled out from under a set of dishes without the dishes being pulled off the table because

  1. The dishes weigh more than the table cloth
  2. The dishes have a tendency to want to remain at rest and do so
  3. The friction force between the table cloth and the dishes is less than the friction between the cloth and the table
  4. The dishes were in a state of static equilibrium and therefore must remain in static equilibrium

6.  Brick A and Brick B are measured to have the same mass. How do their weights on earth compare?

  1. Brick A is heavier than brick B
  2. Brick B is heavier than brick A
  3. The bricks will have equal weight
  4. The bricks will have no weight because support forces balance out the weight

7.  Consider the same two bricks (from #6). If Brick A is taken to the Moon while brick B remains on Earth, how will their weights compare?

  1. Brick A is heavier than brick B
  2. Brick B is heavier than brick A
  3. The bricks will have equal weight
  4. The bricks will have no weight because support forces balance out the weight

8.  Ball A and Ball B are measured to have the same weight. How does the mass of ball A compare to the mass of ball B?

  1. Ball A has more mass than ball B
  2. Ball B has more mass than ball A
  3. The balls will have the same mass
  4. It is impossible to know how they compare since weight cannot inform us about mass

9.  Consider the same two balls (from #8). If Ball A is taken to the Moon while ball B remains on Earth, how will their masses compare?

  1. Ball A has more mass than ball B
  2. Ball B has more mass than ball A
  3. The balls will have the same mass
  4. It is impossible to know how they compare since weight cannot inform us about mass

10.  Consider the same two balls (from #9) with ball A on the Moon and ball B on the Earth. If the balls were rolled toward you at equal speeds, which ball would be more difficult to slow down to a stop?

  1. Ball A
  2. Ball B
  3. The same level of difficulty
  4. It is impossible to know this with the information available

11.  You are a passenger in a car when the driver of the car unexpectedly slams on the brakes. Fortunately, you were wearing your seat belt, but you still experience your head jerk forward. Why?

12.  A marble is fired into a circular tube that has a section cut out as shown. As the marble exits the tube it will follow one of the four labeled paths. Which path will the marble follow? Explain your reasoning.

13.  How much does a 22 kg sack of road salt weigh on Earth?

14.  How much would the same sack of salt weigh on Jupiter where the acceleration due to gravity is about 2.5 times that of the Earth?

15.  What is the mass of a 71.2 N (on earth) bowling ball?