Force can change the speed or direction of motion of an object, or sometimes both. The illustration below shows a game of tug-of-war between two teams of students. The team of students on the right won the contest. What force helped the winning team?

• a balanced force
• an electrical force
• an unbalanced force
• a gravitational force

The forces acting on an object can either be balanced or unbalanced. If an unbalanced force is applied to an object, what might happen to the object?

• only the speed of the object might change
• only the direction of the object might change
• both the speed and direction of the object might change
• neither the speed or direction of the object might change

During the car ride home from school, Peter explained to his father what he learned about motion in class that day. He predicted to his father that they would experience negative acceleration before they arrived home. When did Peter and his father experience NEGATIVE acceleration?

• when they filled the car up with gas
• when they passed another car
• when the drove out of the school parking lot onto the road
• when the approached a stop sign

Rina’s mother asked her to help move some items from the hall closet to the garage. One item she wanted to move was a large box of old school books. Rina tried to lift the box, but could not pick it up. What force was Rina NOT able to overcome?

• frictional force
• electrical force
• gravitational force
• magnetic force

Jorge was riding in the car with his family. Suddenly Jorge shouted out “We just experienced an unbalanced force!” When did Jorge shout this out?

• when their car's engine started
• when their car was passed by another car, while traveling at a constant speed
• when their car slowed down for a red light
• when their car kept on traveling straight along the highway at a constant speed

Melinda is preparing to perform an experiment to test how an unbalanced force affects an object. She plans to use a hair dryer to blow air on a ping pong ball. What two variables should she measure in this experiment?

• force and mass
• direction and time
• mass and speed
• speed and direction

Two students, Priscilla and Devin, are pulling as hard as they can against one another at either end of the rope. Their friend Rod walks by and says they are pulling equally hard. How does he know?

• The rope is making waves.
• Devin is getting rope burn.
• Priscilla and Devin are not moving.
• Priscilla is sliding at a constant rate.

A marine biologist observed the swimming speed of five different types of fish as shown in the chart below. What measurements did the marine biologist take to correctly calculate the speed of these fish?

• time and density
• volume and mass
• distance and time
• distance and density

Kareem set up the materials shown in the illustration below as part of an experiment involving friction. What two instruments will Kareem need to calculate the speed of the book as it slides down the ramp?

• metric ruler and balance
• metric ruler and stopwatch
• balance and stopwatch
• magnifying lens and metric ruler

The graph below plots the distance in kilometers traveled by an object over time in hours. What can you conclude from this graph?

• The speed of the moving object remains constant.
• The speed of the moving object increases over time.
• The speed of the moving object decreases over time.
• The speed of the moving object first increases and then decreases.