Physical Science Unit 8 Review

A boy rubbing his hands together is an example of _____ friction.

• static

• sliding

• fluid

• rolling

Boats have a streamlined shape to reduce _____ friction.

• static

• sliding

• fluid

• rolling

If you try to push a heavy refrigerator across the floor, but you can’t get it started, you’re trying to overcome _____ friction.

• static

• sliding

• fluid

• rolling

Moving a heavy refrigerator on a dolly with wheels is much easier than sliding it across the floor, because you’re changing sliding friction to _____ friction.

• static

• sliding

• fluid

• rolling

If you ride an elevator to the top of a tall building, which of the following changes will occur?

• Your mass will increase.

• Your mass will decrease.

• Your weight will increase.

• Your weight will decrease.

As two objects get closer together, the gravitational force between the objects:

• gets larger

• gets smaller

• does not change

• drops to zero

Debbie, whose mass is 50 kilograms, pushes against a boulder with a constant force of 100 newtons. The boulder’s mass is 5000 kilograms. Which of the following statements is true about the force the boulder exerts against Debbie?

• The boulder exerts no force against Debbie.

• The boulder exerts a force against Debbie, but it is less than 100 newtons.

• The boulder exerts exactly 100 newtons of force against Debbie.

• The boulder exerts a force against Debbie, but it is greater than 100 newtons.

Jonny exerts a net force of 20 newtons against a 10-kilogram stone and against a 5-kilogram stone. Which stone accelerates faster during the time that Jonny is pushing against it?

• The 10-kilogram stone accelerates faster.

• The 5-kilogram stone accelerates faster.

• Both stones accelerate at the same rate.

• Neither stone accelerates at all.

Aaron exerts a net force of 200 newtons against a 100-kilogram crate. Bryan exerts a net force of 400 newtons against a 100-kilogram crate. Whose crate accelerates faster?

• Aaron’s crate accelerates faster.

• Bryan’s crate accelerates faster.

• Both crates accelerate at the same rate.

• Neither crate accelerates at all.

The Amazing Zamboni is performing a magic trick where he yanks the tablecloth from beneath several plates and cups, without knocking anything over. This is possible because of _____.

• momentum

• inertia

• acceleration

• velocity