Physics Forces Practice Quiz

A book rests on a table. The force of gravity pulls down on the book with a force of 20 Newtons. What prevents the book from accelerating downward at 9.8 m/s²?

• The table presses back up on the book with an equal and opposite force of 20 Newtons.

• The table presses back up on the book with a force greater than 20 Newtons.

• The table and the book together are accelerating downwards at 9.8 m/s².

• The inertia of the book holds it up.

One object has twice as much mass as another object. The first object must also have twice as much ____. (Select all that apply.)

• velocity.

• gravitational acceleration.

• inertia.

• weight.

The direction of normal force is always...

• upward

• downward

• perpendicular to a surface

• parallel to a surface

To find the weight of a 50-kg object, you should plug in 50 as the value for ______ and 9.8 as the value for _______.

• F_g; g

• m; g

• m; F_g

• F_g; m

An object experiences two forces - one to the north and one to the west. To find the net force, you should...

• add the forces together

• subtract the westward force from the northward force

• subtract the northward force from the westward force

• use the Pythagorean theorem

The coefficient of friction (μ) can be best described as...

• the amount of force it takes to push an object along a surface

• the roughness of a surface

• the amount of pressure pushing two surfaces together

• a number reflecting the mass of an object

Weight is the same thing as...

• mass

• volume

• gravitational force

• normal force

For a moving object, the direction of friction force is always opposite the direction of...

• applied force

• velocity

• acceleration

• normal force

(Part 1 of 2) A box of weight 100 N is at rest on a level floor where μ = 0.4. A rope is attached to the box and pulled horizontally with a tension force of 30 N to the right. Which way does the box move?

• to the left

• to the right

• up

• down

• it doesn't move

(Part 2 of 2) A box of weight 100 N is at rest on a level floor where μ = 0.4. A rope is attached to the box and pulled horizontally with a tension force of 30 N to the right. What is the magnitude of the net force on the box?

• 0 N

• 10 N

• 30 N

• 70 N

• 104 N