Forces and Motion Concepts

Four students all ran the 10-meter dash at PE. The results are shown below.

According to the data, which student moved at the fastest speed?

• Devon

• Gabrielle

• Cierra

• Declan

Denelle pulled gently on a spring scale attached to a block. The scale showed a force, but the block did not move. Why not?

• The force that she applied was balanced by another force.

• The string between the spring scale and the block was not strong enough.

• The spring scale was broken, so there was no force when she pulled on it.

• There was not enough friction for the block to move.

A rock is balanced on the side of a hill. Although the rock is heavy, a gentle push moves it. How can a small force cause a large mass to move?

• The direction of the force is important to make an object move, but the amount of force is not.

• The push on the rock increased the amount of friction, so the rock moved.

• The small push balanced the forces that were keeping the rock in place and caused it to move.

• The forces on the rock were balanced, and a small additional force caused them to be unbalanced.

Rosa tried to pound a large nail into a board using a small hammer. Partway into the board, the nail stopped. Rosa switched to using a heavier hammer, and the nail went into the board easily. Why did the larger hammer work?

• The nail could not push the larger hammer out of the way.

• There is more friction between a large hammer and the nail.

• The flat part of the larger hammer was wider, so it hit the nail better.

• The larger hammer had more mass, so it exerted more force on the nail.

Which of the following objects will have the greatest change in motion?

• A small force is applied to an object with a large mass.

• A small force is applied to an object with a small mass.

• A large force is applied to an object with a large mass.

• A large force is applied to an object with a small mass.

What must be measured to figure out the speed of a moving object?

• the time it took to travel only

• the distance it traveled only

• the time it took to travel and the distance it traveled

• the direction it traveled and the distance it traveled

The amount of friction an object experiences when it moves depends on the surface it is moving on.

For which of these surfaces will friction be greatest when a block of wood slides across it?

• thick carpet

• wet ice

• glass mirror

• waxed wood

Katherine placed two bar magnets on wheels and put them together as shown.

How will the magnets behave when she releases the bar magnets?

• The magnets will move apart because like poles repel.

• The magnets will move apart because opposite poles attract.

• The magnets will stay together because like poles repel.

• The magnets will stay together because opposite poles attract.

What always changes when an object is in motion?

• position

• direction

• speed

• mass

Tyrell was kicking his soccer ball at recess. He noticed that when he kicked the ball with the same amount of force, it rolled farther on the P.E. court than it did when it rolled across the grass. What force is most likely responsible for this difference?

• air resistance

• friction

• gravity

• magnetism