Unit 2: Force & Motion Review

Sarah has a water slide in her backyard. When the water is turned off, she can barely slide down. But when the water is turned on, she slides very quickly.

Which of the following best explains this observation?

• 1. The water increases the friction between Sarah and the slide.

• 1. The water makes the force of gravity stronger.

• 1. The water pushes Sarah down the slide.

• 1. The water reduces the friction between Sarah and the slide.

A downhill skier wants to reduce his time through a course so that he can make the Olympic team.

Which action would best help the skier reduce friction making him go faster?

• 1. smooth the bottoms of his skis using wax

• 1. eat more food so that he becomes heavier

• 1. get longer skis

• 1. rough up the bottoms of his skis using sandpaper

The picture above shows a hockey puck traveling toward a hockey player in a straight line (dashed black line). If the hockey player hits the puck in the direction of the red arrow,

• 1. the puck will stop.

• 1. the puck will change direction.

• 1. the puck will disappear.

• 1. the puck will keep moving in the same direction.

An object is being pulled to the right. To make the object move to the left, you would have to apply a force to the left that is ​ ​ (a)   ​ the force to the right.

• less than
• greater than
• equal to

A soccer ball is at rest in the center of a field.

If Julia kicks the ball to the right with a large force, what will happen to the ball?

• 1. The ball will not move at all.

• 1. The ball will move in a zigzag pattern.

• 1. The ball will begin to move to the right.

• 1. The ball will begin to move to the left.

An object is moving in a straight line. If an unbalanced force acts on the object, what could happen to the object's motion? Select all that apply.

• The object could begin moving in the opposite direction.

• The object could stop moving completely.
  

• The object could continue moving in a straight line.

• The object could disappear

All objects will slow down as they roll or slide across a surface until they come to a stop. On which surface would a soccer ball slow down and come to a stop the fastest?

• a concrete floor

• a wooden floor

• a sheet of ice

• a grassy field

Kyle and Jon are both pushing the same box. Kyle is pushing to the right. Jon is pushing to the left.

The box will NOT move if

• 1. Kyle pushes the box with more force than Jon.

• 1. Kyle stops pushing the box, but Jon does not.

• 1. Jon and Kyle push the box with the same amount of force.

• 1. Jon pushes the box with more force than Kyle.

Ted designs a test where he uses a spring scale to measure the force required to drag a wooden block over different surfaces, as seen in the image below.

If Jim wants to test the wooden block on a concrete sidewalk and gym floor, what must he do for his test to be fair?

• 1. make sure that each surface is at a different angle to the ground

• 1. make sure that each surface is level

• 1. change the size of the wooden block for each surface

• 1. use different spring scales to test each surface

Ginny and Jack are at a park that has four different tree swings. Each tree swing has a rope of a different length. Ginny measures how long it takes for Jack to swing back and forth one time on each tree swing. The table below shows the length of the rope for each tree swing and how long it takes to swing back and forth one time.

• 4 seconds

• 1 second

• 6 seconds

• 20 seconds