Physical Science 14.1

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You exert a vertical force of 72 newtons to lift a box to a height of 1.0 meter in a time of 2.0 seconds. How much power is used to lift the box? Don't forget the unit for Power!

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Your family is moving to a new apartment. While lifting a box 1.5 m straight up to put it on a truck, you exert an upward force of 200 N for 1.0 s. How much power is required to do this? Don't forget the units!

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You lift a book from the floor to a bookshelf 1.0 m above the ground. How much power is used if the upward force is 15.0 N and you do the work in 2.0 s? Don't forget the units!

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You apply a horizontal force of 10.0 N to pull a wheeled suitcase at a constant speed of 0.5 m/s across flat ground. How much power is used? Don't forget the units!

Multiple Choice

In which of the following cases is work being done on an object?

• pushing against a locked door

• suspending a heavy weight with a strong chain

• pulling a trailer up a hill

• carrynig a box down a corridor

Multiple Choice

A tractor exerts a force of 20,000 newtons to move a trailer 8 meters. How much work was done on the trailer?

• 2,600 J

• 4,000 J

• 20,000 J

• 160,000 J

Multiple Choice

A car exerts a force of 500 newtons to pull a boat 100 meters in 10 seconds. How much power does the car use?

• 5000 W

• 6000 W

• 50 W

• 1000 W

Multiple Choice

One horsepower is a unit of power equal to

• 0.746 W

• 1.0 W

• 746 W

• 2,000 W