Answers NC-Physical ScienceUnit Test

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Which set of terms best defines what affects kinetic energy and potential energy, respectively?

position, gravity

gravity, velocity

velocity, height

height, position

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Which term is the product of force and distance?

power

work

net force

acceleration

What is needed for work to be done?

A force must push on an object without moving it.

A force must pull on an object without moving it.

A force must cause an object to move along the same direction as the force.

A force must act on an object while an equal force acts oppositely on the object.

Seema knows the mass of a basketball. What other information is needed to find the ball’s potential energy?

the volume and height the ball reaches

the volume and shape of the ball

acceleration due to gravity and the height the ball reaches

acceleration due to gravity and the shape of the ball

What is the source of almost all energy on Earth?

Earth’s hot core

the Sun

stored carbon

moving water

As a person pushes a box across a floor, the energy from the person’s moving arm is transferred to the box, and the box and the floor become warm. During this process, what happens to energy?

It is increased.

It is conserved.

It is decreased.

It is created.

Adita lifts a book from the floor, carries it across the room, and places it on a high shelf. When is Adita doing work on the book?

She does work on the book at no time during this process.

She does work only while she carries the book across the room.

She does work from the moment she touches the book until she lets it go.

She does work as she picks up the book and as she lifts it to the shelf.

Simone created a chart to summarize the energy transformations that take place when energy from the wind is used to generate electricity.Which best completes the chart?

nuclear energy transformed to electrical energy

chemical energy transformed to electrical energy

radiant energy transformed to mechanical energy

kinetic energy transformed to mechanical energy

When a person strikes and lights a match, potential energy in the match is transformed into which types of energy?

electrical and thermal

thermal and radiant

radiant and nuclear

nuclear and kinetic

The table shows information about four students who are running around a track. Which statement is supported by the information in the chart?

Autumn has more kinetic energy than Chiang.

Mohammed has less kinetic energy than Autumn.

Lexy has more kinetic energy than Mohammed.

Chiang has less kinetic energy than Lexy.

If the kinetic and potential energy in a system are equal, then the potential energy increases. What happens as a result?

Total energy increases.

Stored energy decreases.

Energy of motion decreases.

Total energy decreases.

A powered winch is used to pull a sailboat to shore. The winch uses a 900 W motor.If the motor is used for 30 s, how much work does it do? (Power: P = W/t)

0.03 J

30 J

960 J

27,000 J

Plants are responsible for a very important energy transformation, as shown.

radiant to chemical

nuclear to mechanical

chemical to thermal

mechanical to chemical

Shani poses as the Statue of Liberty for an art class. She holds a torch above her head with her right hand and a book against her side with her left hand. She holds the pose for ten minutes. At the end of the session, she mentions to her friend that it was a lot of work to pose and that her arms are really tired.Which describes the work Shani did while she posed?(assume the starting work position is when her hand is already raised )

She did more work with her right hand than with her left because the right was held up higher.

She did no work while she posed because she did not move the torch or the book.

She did work while she posed because she was tired at the end of the session.

She did no work while she posed because she did not exert a force on anything.

What happens in terms of energy when a moving car hits a parked car, causing the parked car to move?

The moving car transfers kinetic energy to the parked car.

Kinetic energy in the moving car disappears.

Kinetic energy in the parked car is created.

The parked car transfers kinetic energy to the moving car.

Joshua programs a robotic arm to place a block in a box by following the sequence of commands in the table.During which step does the robotic arm do work on the block?

Step 1

Step 2

Step 3

Step 4

Olivia is on a swing at the playground.

Energy can be transformed from one form to another. The diagram shows one such process.

nuclear to thermal and radiant

nuclear to electrical and chemical

chemical to nuclear and radiant

chemical to electrical and nuclear

Which activity directly converts energy from the Sun into chemical energy?

a snake lying on a sunny rock to keep warm

a rabbit using energy from food it has eaten to run

a bean plant making its own food to grow

a person burning firewood to cook food

Power is measured in which unit?

joules

watts

meters per second

newtons per meter

If 600 J of work is done in 3 s, what is the power? (Power: P = W/t)

0.005 W

200 W

603 W

1800 W

A gust of wind blowing east pushes against a ball. When will the wind do work on the ball?

when the ball moves to the east

when the ball moves to the north

when the ball stays in one place

when the ball moves north or south

The diagram shows a swinging pendulum.

The pendulum will slow down and eventually stop moving as the mechanical energy transforms to thermal energy.

The pendulum will slow down and eventually stop moving as the mechanical energy disappears.

The pendulum will continue moving at the same speed because mechanical energy is created as the pendulum moves.

The pendulum will slow down but will not stop moving because some of the mechanical energy is destroyed.

Pablo prepares to lift a barbell. During which stage of the lift does Pablo do work on the barbell?

when he holds the barbell up above his head

when he applies force to the barbell but has not moved it

when he lifts the barbell from the floor to his chest

when he lets go of the barbell and allows it fall to the ground

Den pushes a desk 400 cm across the floor. He exerts a force of 10 N for 8 s to move the desk.What is his power output? (Power: P = W/t)

1.25 W

5 W

40 W

500 W

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