Forces and Free Body Diagrams

What is inertia?

• The ability of an object to resist changes in motion

• The movement of an object

• Another name for the kinematic equations

What does Newton's 1st Law state?

• F = ma

• An object at rest will stay at rest, an object in motion will remain in motion unless acted upon by a net force

• For every action force, there is an equal and opposite reaction force

What are the two equilibrium cases for forces acting on an object? (Select all that apply.)

• When the object is moving at a constant velocity

• The object is speeding up

• The object is at rest

• The object is slowing down

Which of the following free body diagrams correctly depict the forces acting on an object that is moving at a constant velocity?

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Tags

NGSS.HS-PS2-1

Two people are pushing on a 20 kg box. One person is applying a force of 100 N to the left. The second person is applying a force of 150 N to the right. What is the net force acting on the box?

• 250N

• 100N

• 50N

• 150N

A car is exerting a force of 200N to the right and some kids are pushing it to the right with 175N. What is the net force?

• 200N

• 175N

• 25N

• 375N

Javier kicks a soccer ball, which hits a wall. Which of the following statements are true, based on Newton's 3rd law?

• The wall exerts a bigger force on the ball, because the ball has a smaller mass.

• The ball exerts a bigger force on the wall, because it has the bigger acceleration.

• Each object exerts the same force on each other, but are in opposite directions.

• Not enough information.

If a force is applied to an object and it is not moving, how would you describe the force?

• The net force is moving upward.
• The net force is moving to the right.
• The net force is zero.
• The net force is 50.

A push or a pull is .....

• Force
• Inertia
• Net force
• Newton

What is the action force and the reaction force when you sit down on a chair?

• Action=chair pushes back on you; Reaction=sitting down

• Action=sitting down; Reaction=chair pushes back on you

• No reaction; Action=sitting down and the chair pushes back on you

• No action; Reaction=sitting down and the chair pushes back on you