Forces and Energy

What is a force?

• a pull exerted on an object

• a measure of how heavy an object is

• a push or a pull exerted on an object

• a change in the direction of motion of an object

Tags

NGSS.MS-PS2-1

Sasha pulls a block across the floor at a constant speed. Why doesn’t the motion of the block change even though Sasha is pulling on it?

• Sasha’s force on the block is balanced by the friction force.

• Sasha’s force on the block is balanced by the gravitational force.

• If Sasha was not pulling on the block, there would be no forces on the block, and it would speed up.

• If Sasha was not pulling on the block, there would be no forces on the block, and it would stop moving.

Tags

NGSS.MS-PS2-2

When a comet enters the solar system, it curves toward the sun. Which statement describes why the sun does not move when a comet is nearby?

• There is no force exerted on the sun from the comet.

• There is no force exerted on the sun unless the sun and comet collide.

• The force on the sun from the comet is smaller than the force on the comet from the sun because the comet’s speed is too great.

• The force on the sun from the comet is equal to the force on the comet from the sun but does not cause the sun to move because the sun is too massive.

Tags

NGSS.MS-PS2-4

NGSS.MS-PS2-5

The weights of four objects with different masses have been calculated to show how much each object would weigh on four different planets.

Based on the table, which object would have the largest mass and greatest weight on Earth?

• Object A

• Object B

• Object C

• Object D

Tags

NGSS.MS-PS2-4

NGSS.MS-PS2-5

Rebecca is practicing her aim by throwing a ball at a target.

The ball exerts a force on the target, causing the target to fall over. But when this happens, the ball bounces backward. Why does the ball bounce backward?

• The target exerts a larger force on the ball because the ball is very bouncy.

• The ball exerts a larger force on the target, causing the target to have a larger change of motion than the ball.

• The target exerts the same size force on the ball, so when the target moves in one direction, the ball moves in the opposite direction.

• The ball exerts a smaller force on the target because the ball is smaller than the target, so the target causes the ball to bounce backward.

Tags

NGSS.MS-PS2-1

The diagram shows four blocks suspended on identical dynamometers, a tool that is used for measuring the weights of objects.

Which object has the greatest weight?

• object A

• object B

• object C

• object D

Tags

NGSS.MS-PS2-4

Is gravity a contact force or a noncontact force?

• contact force

• noncontact force

Tags

NGSS.MS-PS2-5

Is friction a contact force or a noncontact force?

• contact force

• noncontact force

Is air resistance a contact force or a noncontact force?

• contact force

• noncontact force

Tags

NGSS.MS-PS2-5

Is pushing with your hands a contact force or a noncontact force?

• contact force

• noncontact force