Work and Power

A couch is pushed with a horizontal force of 80 N and moves a distance of 5 m across the floor. How much work is done in moving the couch? (The last space is the unit.)

(a)  

How much work do you do when you lift a 100 N child 0.5 m?

(a)  

The brakes on a car do 240,000 J of work in stopping the car. If the car travels 40 m while the brakes are being applied, how large is the average force that the brakes exerted on the car?

(a)  

Tags

NGSS.MS-PS2-2

Match the variables with the correct answer.

W = F x d

• 10 m

• F = 20 N

  d = 5 m

• 3 N

• F = 8 N

  d = 4 m

• 32 J

• W = 15 J

  d = 5 m

• 100 J

• W = 20 J

  F = 2 N

The equation for work is

work = ​ (a)   x ​ (b)  

• force
• distance
• mass
• acceleration
• velocity

If you push against an object and it doesn't move, are you doing work?

• No

• Yes

When the force is perpendicular to the motion, the work being done is 0.

• True

• False

You do 90 joules of work in 30 seconds. How much power have you generated?

• 30 watts

• 3 watts

• 120 watts

• 270 watts

If 68 W of power is produced in 18 seconds, how much work is done?

• 1,224 J

• 0.264 J

• 3.77 J

• 12.24 J

Tags

NGSS.HS-PS3-1

How much time is needed to produce 720 Joules of work if 90 watts of power is used? 

• 0.125 s

• 8 s

• 64800 s

• 80 s

Tags

NGSS.MS-PS3-5