Physics Review

Forces can cause changes to a body. Select all the changes, from those listed below, that can be caused by a force.

• a ball moving across a table comes to a halt

• a piece of iron goes from black to red-hot

• a train slows down and stops

• our moon moves around the Earth at constant speed

• solid iron ore is converted to liquid iron

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NGSS.HS-PS2-1

What is the name given to the idea of how much useful work is done by a sytem compared to how much energy has is supplied to that system?

• Newton's first law

• how fast work is done

• power

• efficiency

A falling skydiver, whose weight is 800 N, is experiencing air resistance of 600 N. Which one of the following statements about this skydiver is correct?

• She has a constant speed and the net force on her is 200 N down.

• The net force on her is 200 N up and she is slowing down.

• She is speeding up and the net force on her is 0 N.

• The net force on her is 200 N down and she is speeding up.

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NGSS.HS-PS2-1

A falling skydiver, whose weight force 800 N, is maintaining a steady downwards speed (the speed is not changing, it is called "terminal velocity"). Which of the following statements is true?

• The wind must blowing strongly

• Air resistance has become 800 N

• Air resistance has stopped.

• Air resistance is 600 N

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NGSS.HS-PS2-1

NGSS.HS-PS2-2

In which of the following situations is work being done on the object mentioned? Select all that apply.

• A box is lifted to two metres up from the floor.

• A stuck car is pulled with a rope, without moving.

• A chair is pushed across the room.

• A 20 kg mass rests on a table.

• A boy holds a drawn bow with an arrow on it, ready to shoot.

A bicycle and rider are moving in a straight line, along a level road, and their speed is not changing. Which statement about the bicycle and rider must be correct?

• The wind resistance is greater than the weight force of the bicycle and rider.

• The forward push from the cyclist is less than the opposing forces.

• There is no net force acting on the the bicycle and rider.

• The forward push from the cyclist is more than the opposing forces.

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NGSS.HS-PS2-1

NGSS.HS-PS2-2

Which statement is true about power?

• Power is, how much work is done.

• Power is, how fast work is done.

• Power is, force times distance moved.

• Power is weight times gravity.

Two brothers pull against each other on a rope, tug-of-war like. Malik pulls with 450 N force and Isaac pulls with 600 N force. Which statement is correct?

• There is no net force, they stay where they are.

• There is a net force of 150 N towards Isaac, they move in Isaac's pulling direction.

• There is a net force of 150 N towards Malik, they move in Malik's pulling direction.

• There is no net force, they move in Isaac's pulling direction.

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NGSS.HS-PS2-1

• 40%

• 60%

• 10%

• 90%

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NGSS.HS-PS3-1

NGSS.HS-PS3-4

• 250 000 J

• 400 J

• 40 000 J

• 2 500 J

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NGSS.HS-PS3-1