Ch 10 Review Questions Motion

A boat was traveling at 15 mph when a passenger threw an object at 10 mph in the same direction the boat was moving. A friend, standing on the shore, observed the object moving with a speed of 25 mph. The passenger observed the object moving with a speed of 10 mph. Why were the two observations different?

• The current of the river affects the speed of the boat relative to shore.

• Objects appear to move more slowly when they move away from the observer.

• The passenger and the friend were watching the object from two different frames of reference.

• The distance between the boat and the shore gave the friend a different viewing angle.

Over a period of 2.50 seconds, a speedboat accelerates uniformly from 18.5 m/s to 46.5 m/s. What is the acceleration of the speedboat relative to the shore?

• –28 m/s²

• 28 m/s²

• –11.2 m/s²

• 11.2 m/s²

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NGSS.HS-PS2-1

A boat is moving at a speed of 7 m/s relative to the water. A dog walks from the front to the back of the boat at a speed of 2 m/s relative to the boat. What is the speed of the dog, in m/s, relative to the water?

• 3.5 m/s

• 5 m/s

• 9 m/s

• 14 m/s

A Mars Rover has been sent to explore and relay data from Mars. Mars is less massive than Earth. When compared with Earth, which is the BEST comparison between the mass and the weight of the Rover on Mars?

• The mass is more on Mars and the weight is less.

• The weight is more on Mars and the mass is less.

• The weight is less on Mars and the mass is the same.

• The mass is less on Mars and the weight is the same.

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NGSS.MS-PS2-4

A ball at rest is dropped and hits the ground in 1.5 s with a final speed of 15 m/s. How would the acceleration and final speed of the ball be affected if it were dropped from a greater height on Earth? (Ignore friction.)

• Its final speed would remain the same because its rate of acceleration would remain the same.

• Its final speed would increase because its rate of acceleration would remain the same.

• Its final speed would remain the same because its rate of acceleration would decrease.

• Its final speed would increase because its rate of acceleration would increase.

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NGSS.HS-PS2-1

Student X pushes a 10-N box with a force of 2 N. At the same time, Student Y pushes the same box with a force of 6 N, but in the opposite direction. Which would most likely occur? (Ignore friction.)

• The resultant force on the box would be 8 N.

• The resultant force on the box would be 18 N.

• The box will move toward Student X.

• The box will move toward Student Y.

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NGSS.HS-PS2-1

The action of swimmers using their arms to propel themselves through the water is an example of what law?

• Newton’s first law of motion

• Newton’s third law of motion

• law of conservation of linear momentum

• law of conservation of angular momentum

Which of these is an example of sliding friction?

• a badminton shuttlecock flying over the net

• a basketball rolling across a wooden floor

• a flying kite pushed by a gentle breeze

• a hockey puck moving across the ice

Which sentence correctly describes a friction force?

• It acts in the same direction as the motion of an object.

• It acts in a direction opposite to the motion of an object.

• It acts in a direction perpendicular to the motion of an object.

• It acts in the same direction as the force of gravity on an object.

A student pushes a book with a force of 5 N to the east. Which statement describes the reaction force?

• 5N eastward, acting on the book

• 5N westward, acting on the book

• 5N eastward, acting on the student

• 5N westward, acting on the student

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NGSS.HS-PS2-1