Force and Motion Review

A student pushes a hollow ball with a small amount of force causing it to roll quickly across the room.  The student then pushes a solid ball with the same amount of force.  

Which statement demonstrates an understanding of force and its effects on an object?

• The force on both balls was the same; therefore each ball pushes back with the same amount of force.

• 
  The force on both balls was the same; however each ball pushed back with a different amount of force.

• The solid ball pushes back with greater force than the hollow ball, because the solid ball has greater mass.

• The hollow ball pushes back with a greater force than the solid ball, because the solid ball moved faster and further.

Which of these would NOT change the velocity of an object?

• The object speeding up as more force is applied.

• The object slowing down as it is going up a hill.

• The object maintaining constant speed and direction.

• The object turning right.

The balls have different masses but travel with the same speed.

Which ball will hit the wall with the greatest amount of kinetic energy?

• the ball with mass 0.145 kg

• the ball with mass 0.046 kg

• the ball with mass 0.624 kg

• the ball with mass 0.057 kg

Juno, Melissa, and Anna have skateboards that are the same mass.  They were playing with their skateboards on a flat street when another skateboard came along and bumped their skateboards, but not from the same direction.  Each skateboard changed speed as a result of being bumped.  us the information in the diagram to answer the question.
Use the information in the passage and diagram to answer the question.

Which skateboard(s) experienced the strongest force when bumped?  How do you know?

• The green skateboard experienced the strongest force because it changed speed the most.

• The green skateboard experienced the strongest force because it takes up a stronger force to slow something down than it takes to speed something up.

• The red and brown skateboards experienced the same strength force because they both gained force, but the green skateboard lost force.

• The red skateboard experienced the strongest force because it has the fastest ending speed.

The three skiers were racing across flat, smooth snow.  The skiers in yellow and purple sweaters have the same mass, which is more mass than the skier in the red sweater.  Each skier was bumped by another skier, but not from the same direction.  Use the information in the diagram to answer the question.
Use the information in the passage and diagram to answer the question.

Which skier(s) experienced the strongest force when bumped?  How do you know?

• All three skiers experienced the same force because they changed speed the same amount.

• The purple skier; he is more massive and has the fastest ending speed.

• The yellow skier; it takes a stronger force to slow down a more massive object than to speed it up.

• The yellow and purple skiers; they have more mas then the red skier, but changed speed by the same amount.

A shopping cart is at rest on the floor.  Assume that there is no friction.
What will happen to the motion of the shopping cart immediately after the unbalanced force is removed?

• 
  The cart will begin to gain speed.

• The cart will be set in motion. 

• The cart will continue to move at a constant speed.

• The cart will begin to slow down.

Hannah just finished building a house of cards that stands four stories high.  She is worried that it will fall down.

Which of the following statements is definitely true?

• 
  As long as nobody touches the house of cards, it will remain standing.

• 
  A house of cards is too fragile and must fall down eventually.

• If no unbalanced force acts upon the house of cards, then it will remain standing forever.

• If Hannah adds another card to the house of cards, then it will fall down.

A cylindrical object is at rest on a table.  Assume that there is no friction.
To balance the forces on the cylindrical object, the student removes the unbalanced force being applied to it.

What will happen immediately after this force is removed?

• The object will begin to gain speed.

• The object will begin to slow down.

• The object will continue to move at a constant speed.

• The object will be set in motion.

A polar bear walks on sea ice t hunt prey living in the water.  

Which statement best describes an interaction between the polar bear and the sea ice?

• The force applied by the polar bear is less than the force applied by the sea ice.

• The force applied by the polar bear is greater than the total force applied by the sea ice.

• The polar bear applies no force to the sea ice because the sea ice applies a force to the polar bear.

• The polar bear applies a force to the sea ice, and the sea ice exerts an equal and opposite force on the polar bear.

Engineers are designing a new car and they need to test their ideas by modeling crashes with different types of trucks.  They are using a more massive garbage truck for Crash 1 and a less massive pickup truck for Crash 2.  The green test car has the same mass in both crashes.  

In which case did the green test car experience a stronger force?  How do you know?

• 
  Crash 1:  the force on the garbage truck was stronger in this crash, so the force on the green test car was also stronger.

• There is no force on the green car.  In each crash, only the truck experienced a force.

• It was the same from both crashes.  The trucks changed speed by the same amount in both crashes, so the force on the test car was the same both times. 

• The diagram doesn't tell you anything about the force on the green test car.  It only gives information about the force on the trucks.