Forces and Motion

When is it clear that balanced forces are acting

on an object?

• The object begins moving.

• The object's motion changes direction.

• The object stops moving.

• The object's motion does not change.

Bobby's wagon started rolling down the hill.

Which forces can change the motion of the

wagon?

• Magnetic force can slow the wagon, and normal

  force can speed it up.

• Normal force can slow the wagon, and frictional

  force can speed it up.

• Frictional force can slow the wagon, and

  gravitational force can speed it up.

• Gravitational force can slow the wagon, and

  frictional force can speed it up.

Nelda walks from the Big Pine neighborhood to

school every morning. Jonah walks from the

Stone Creek neighborhood to school every

morning. They both leave at the same time, but

Nelda always arrives before Jonah. What other

information is needed to determine who walks

the fastest?

• the direction each child walks

• the distance between Nelda's and Jonah's

  neighborhoods

• the weight of each child's backpack

• the distance between each neighborhood and

  the school

An object with increasing acceleration is also

increasing in which other property?

• volume

• mass

• velocity

• temperature

A car travels 40 miles north in the first 40 minutes

of a trip. The same car travels 30 miles west in

the next 30 minutes of the trip. What can be said

about the motion of the car?

• The car is moving at a constant velocity.

• The car is decreasing its speed.

• The car is traveling at a constant speed.

• The car is accelerating at a constant rate.

A car is traveling 20 kilometers an hour, then

changes direction at a fork in the road. The action

that the car takes changes its

• velocity, but not its speed.

• speed, but not its velocity.

• speed, but not its acceleration.

• acceleration, but not its velocity.

How does gravity affect the amount of force one

must use to lift an object?

• As the object gets heavier, less force will be

  required.

• One must use a force less than the force of

  gravity to lift an object.

• As the object is lifted higher, more force will be

  required.

• One must use a force greater than the force of

  gravity to lift an object.

Newton's first law of motion states that an object

at rest will remain at rest or an object in motion

will remain in a constant motion, unless acted on

by an outside force. Another name for this law is

the

• law of momentum

• law of inertia

• law of gravity

• law of acceleration

A car is driving down the road at a constant

speed. Which of the following is true about the

forces acting on the car?

• The normal force of the tires is greater than the

  force of motion of the car.

• The force of gravity on the car is greater than the

  normal force of the car.

• The friction force of the tires is greater than the

  force of gravity from the road.

• The force of motion of the car is greater than the

  force of friction from the road.

Amy placed a small television on a metal rolling

cart. On her way to the library, her friend Carlos

stepped in front of the cart. Even though Amanda

stopped suddenly, the television stayed in place

on the cart. Which of the following most likely

kept the television on the cart?

• friction

• magnetism

• buoyant force

• air pressure