Forces and Motion Review #1

Isaac Newton discovered the three laws of motion. Which example BEST illustrates Newton’s third law of motion, which describes action and reaction forces?

• a rocket takes off from the ground

• a book slides forward on a seat when the car stops

• a heavier ball falls at the same speed as a lighter ball

• a vehicle rounds a curve and changes its acceleration

A boat moves forward through water with a force of 5,100 newtons (N). The water resists with forces equaling 4,800 N. What is the net force acting on the boat?

• 300 N

• 4,800 N

• 5,100 N

• 9,900N

Dennis conducted an investigation on the effect of friction on a toy car. Dennis had a ramp that he moved onto four different surfaces. During each trial, he rolled the toy car down the ramp and measured the distance the car traveled from the bottom of the ramp. He repeated the investigation three times on each surface. His data are shown in the table.

Based on Dennis’s results, what should he conclude?

• The toy car rolled farther on gravel than on sand

• The toy car rolled the greatest distance on wood.

• The toy car rolled the shortest distance on gravel.

• The toy car rolled farther on sand than on blacktop.

The BEST example of balanced forces is a

• car increasing speed.

• bus parked in a garage.

• ball kicked along a flat surface.

• roller coaster slowing down on an incline.

A student pushes a box to slide it across the floor. Which statement explains why the box begins to move?

• The weight of the box is greater than the force of friction.

• The weight of the box is less than the force of friction.

• The applied force is greater than the force of friction.

• The applied force is less than the force of friction.

A car runs out of fuel while traveling on a level road and eventually comes to a stop. Which of the following BEST explains why the car stops?

• Some of the energy of the car was lost to friction.

• Some of the energy of the car was destroyed.

• The amount of kinetic energy increased.

• The amount of useful energy increased.

When the first American astronauts were planning to walk on the Moon, they knew that the gravity on the Moon was less than the gravity on Earth. With this information, what did the astronauts expect to be MOST different on the Moon?

• their mass

• their height

• their weight

• their volume

A swimmer swims across a pool, and at the end the pool she turns around and pushes off the wall with her feet. Which option describes a pair of action-reaction forces during the push?

• the force of her feet on the wall and the force of the wall on her feet

• the force of gravity on her body and the force of her feet on the wall

• the force of gravity on her body and the force of the wall on her feet

• the force of her feet on the wall and the force of the water on her front

A cart accelerates at a rate of 5.0 m/s² when acted on by a net force of 25 N. What is the magnitude of the acceleration of the cart when acted on by a force of 75 N to the east and 35 N to the west at the same time?

• 7.0 m/s²

• 8 m/s²

• 15 m/s²

• 22 m/s²

Max pushed and released a toy dump truck on a flat sidewalk. The truck traveled for a long distance and stopped when it hit a wall. Which BEST explains why the truck traveled the long distance to the wall?

• The truck had inertia due to its mass.

• Gravity pulled the truck to the wall.

• Magnetism pulled the truck to the wall.

• The sidewalk applied friction to the truck.