Work and Power

Tina and her puppy are tugging on a rope, each pulling on opposite ends. When is Tina doing work?

Whenever she pulls the puppy toward her.

When work is measured in joules and time is measures in seconds, power is measured in __________

watts

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

200 W

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 10 minutes. At the end of the session, she mentions to her friend that it wa

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

A lawnmower engine running for 20 mins does 4,560,000 J of work. What is the power output of the engine? (Power: P = W/t)

NOT
228,000 W

What is needed for work to be done?

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

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

When he lifts the barbell from the floor to his chest.

Sierra did 500 J of work to move her couch. If she exerts 250 N of force on the couch, how far did she move it? (Work: W = Fd)

2 m

The rate at which work is done is called ________

NOT
"Joule

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

Step 2

Henry can lift a 200 N load 20 m up a ladder in 40 s. Ricardo cab lift twice the load up one-half the distance in the same amount of time. Which comparison between Ricardo and Henry is correct?

Ricardo exerted a greater force, did the same amount of work, and had the same power output as Henry.

A force acts on an object and moves it a certain distance. The product of the force and the distance is the _______ done on the object

work

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.

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)

NOT
1.25 W