Power

Power

...It's all about the time!

Let's remember...

Work = Force x distance

• The object must move

• The force and object must move in the same direction

Multiple Choice

Is it work?

A box is carried?

• YES

• NO

Multiple Choice

Is it work?

Pushing a lawn mower

• YES

• NO

Multiple Choice

Is it work?

Trying to move a big boulder (rock)

• YES

• NO

Multiple Choice

Is it work?

Lifting weights

• YES

• NO

Multiple Choice

Calculate work if a boy pushes a toy car across a floor a distance of 2m with a force of 10N.

• 20 J

• 5 J

• 12 J

• No work was done

Multiple Choice

Calculate work if a girl carries her lunch tray with a force of 10 N a distance of 2 m.

• 20 J

• 5 J

• 12 J

• No work was done

What is Power?

• The rate that work is done

• (How FAST work can be done)

Power formula

• Power = Work / Time

• (P = W/t)

POWER Unit

• Watts (W)

• OR (Joules per second)

Multiple Choice

Which of the following is TRUE about power?

• Power is how much force is used

• Power is how fast work can be done

• Power is how far an object is moved

Multiple Choice

What is the formula to calculate power?

• P = W x t

• P = W / t

• P = W + t

• P = F x d

Multiple Choice

What is the correct UNIT for power?

• Joule

• Watt

• Newton

• meters

Multiple Choice

Calculate POWER:

Work = 100 J

time = 2 seconds

• 50

• 50 W

• 200 W

• 200 J

Multiple Choice

A man throws a baseball doing 500 J of work in 2.5 seconds. How much power did he have?

• 12500

• 1250 W

• 200 W

• 200 J

You may need to find work first....

Then power

• W = F x d

• P = W/t

Multiple Choice

A girl pushes a lawn mower with a force of 50N a distance of 100m in 500s. How much power did the girl have?

• 10 W

• 5000 W

• 0.5 W

• 1000 W

Multiple Choice

An elevator uses 2000N to lift passengers 10m in 5 seconds. How much power does the elevator have?

• 4000 W

• 20,000 W

• 1000 W

• No power

Multiple Choice

An delivery driver carries a stack of boxes with a force of 25N a distance of 3m in 20 seconds. How much power does the delivery driver have?

• 167 W

• 3.75 W

• 2.4 W

• No power

Multiple Choice

Messi kicks a soccer ball a distance of 18m in 2 seconds. He uses a force of 50N. How much power does Messi have?

• 5.55 W

• 0.72 W

• 450 W

• No power

Multiple Choice

Marcos tries to move a piece of furniture with a force of 100N a distance of 1.5m. He tries for 20 seconds but is unable to move the furniture. How much power does he have?

• 7.5 W

• 1,333 W

• 0.3 W

• No power

Multiple Choice

Messi can dribble a ball 25m in 2.5 seconds.

Ronaldo can dribble a ball 25m in 5 seconds.

Who is more powerful?

• Messi because he used less time

• Ronaldo because he used more time

• They have the same power

• Ronalod because he used less time