Force and Motion

A ball rolls down from the top of a grassy hill, reaches the bottom of the hill, continues to roll, and then starts to slow down and comes to a stop.  What forces caused the ball's motion?

• Friction caused it to roll down the hill, air resistance caused the ball to slow down and stop.
• Magnetic force caused the ball to roll down the hill but gravity caused it to slow down and stop.
• The force of the hill caused the ball to roll down it but gravity caused the ball to slow down and stop.
• Gravity caused the ball to roll down the hill but friction caused the ball to slow down and stop.

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If a spring is attached to two boards with one board at each end of the spring and the two boards are pulled far apart to stretch the spring, what force will the spring exert in response?

• It will sag between the two boards
• It will pull the boards toward each other
• It will hold the boards steady in one piece
• It will spin the boards in opposite directions

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The picture below shows a compass.  The needle in the middle of a compass is a magnet.
If the needle on a compass turns when a person changes position on the Earth, what force is acting on the compass?

• Magnetic force at Earth's polls
• Gravitational force from Earth's center
• Frictional force from Earth's surface
• Gravitational force at Earth's polls

Science students are conducting an investigation.  They prepare three level surfaces.  The first surface is smooth, the second surface is sandpaper, and the third surface is carpet.
Which of the following forces can the investigation test?

• electrical
• friction
• gravitational
• magnetic

Which two variables determine the gravitational force between two objects?

• their masses and weights
• their masses and the distance separating them
• their masses and magnetic strengths
• their densities and the distance separating them

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The picture shows 4 friends climbing a mountain.  If all 4 friends weigh the same amount, which person feels the least pull  of gravity from the Earth?

• Allison
• Benjamin
• Callie
• Dennis

Which statement correctly describes the factors affecting gravitational force between two objects?  
They're determined by...

• It's determined by their diameters and their distance from the Sun
• Their masses and the distance between their centers
• Their volumes and their acceleration relative to the Sun
• Their masses and the distance between their outermost edges

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If you were orbiting Earth, you would weigh less than you do standing on Earth. Why would your weight in orbit be lower than your weight on Earth’s surface?

• There would be too great a distance between you and Earth for gravity to have any effect
• There would be a greater distance between you and Earth, and gravity is related to distance
• You would have more mass in orbit, and gravity is related to mass
• The gravities of satellites and other objects in orbit around Earth would contribute to your weight while you were in orbit

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Which of these has an unbalanced force?

• a book sitting undisturbed on a desk
• a child standing in a line that is not moving
• a ball slowing down as it rolls on the ground along a straight line
• a meteoroid moving at a constant speed and direction through outer space

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The diagram shows forces acting on a model airplane.  Both its speed and height above the ground are constant.
What conditions would cause the airplane to descend toward the ground?

• The lift is equal to the drag
• The lift is less than the weight
• The thrust is equal to the weight
• The thrust is greater than the drag

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