PS - Chapter 12 - Dynamics

What is a force?

• a collision of two objects

• a push or pull on an object

• the motion of objects

• the resistance of two objects when they touch each other

What is the unit of force?

• galileo

• newton

• kg·m

• m/s²

Which of the following is a contact force?

• electric force

• friction force

• gravitational force

• magnetic force

Which of the following is the result of a field force?

• A tossed ball falls to the ground.

• An apple press squeezes out apple cider.

• An airplane is jostled because of wind shear.

• The eighth graders win against the ninth graders in tug of war.

Multiple, simultaneous forces that cancel each other out are called __________ forces.

• balanced

• unbalanced

• acclerating

• summative

Any change in motion must be initiated by a(n) __________ force.

• balanced

• field

• contact

• unbalanced

How is the magnitude of a force represented in a free-body diagram?

• by the length of the arrow

• by the location of the arrowhead

• by the number of arrows

• by the width of the arrow

Which discovery allowed Isaac Newton to build on Galileo’s concept of inertia?

• accurate balances

• accurate clocks

• electricity

• subatomic particles

Which object remains in its current state unless acted upon by a net external force?

• an object at rest

• an object in motion

• an object with constant velocity

• all the other answers

The law of inertia states that:

• any object with mass also has inertia.

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

• objects will remain in their current state unless acted on by a net external force.

• the acceleration of an object is directly proportional to the net force acting on the object.