Force & Motion

A train rolls to a stop along a horizontal track without the conductor applying the brakes. What answer choice BEST explains why this occurred?

• The train ran out of momentum.
• The opposing force of friction stopped the train.
• The natural state of the train is not to be in motion.
• The force of gravity slowed the train until it stopped.

2) The motion of the earth around the sun is best described as

• curved motion
  
• vibrating motion
  
• projectile motion
  
• straight line motion
  

3) What would be an ideal experiment to test how different types of surfaces affect friction?

• Two objects of equal weight placed on two glass surfaces of equal lengths.
  
• Two objects of equal weight placed on two glass surfaces of unequal lengths.
  
• Two objects of equal weights placed on a glass surface and a wooden surface.
  
• Two objects of different weights placed on two wooden surfaces of unequal lengths.
  

When Jackson throws a baseball in a straight path, what two forces cause the ball to eventually stop moving?

• gravity and friction
  
• mass and ground force
  
• wind resistance and mass
  
• negative acceleration and gravity
  

Jamie pushed and pushed on the refrigerator but it would not budge! Jamie wondered what he could do to help move the heavy refrigerator. He thought about seeing the movers use a dolly with wheels to help move boxes and heavy furniture to their moving truck. Jamie did not have a dolly but he thought maybe he could put something under the refrigerator to help move it.
What would be a testable question Jamie could use to begin his investigation?

• How do wheels help things move?
  
• Why is it so hard to push the refrigerator?
  
• What can I put under the refrigerator to help it move?
  
• The heavy refrigerator needs wheels so it can move easily.
  

6) Sam is pushing a large rock over the ground. All BUT ONE of the following terms relates to the movement of the rock. What term is it?

• force
• friction
• mass
• size

7) The force that slows down and eventually stops a ball you roll across the pavement is called

• kinetic force.
  
• friction force.
  
• the slow force.
  
• potential force.
  

How fast an object is moving is its

• direction
• motion
• position
• speed

9) Forces that are equal in strength and opposite in direction are

• balanced forces
• unbalanced forces
• always result in motion.
• always the result of motion.

10) After it snowed, a truck spread sand over a road. How does sand help cars drive on a road that has snow or ice?

• Sand increases friction.
• Sand decreases friction.
• Sands helps cars speed up.
• Sand reduces the pull of gravity.