Power review

_____ is the speed or rate of doing work

• Newton

• Energy

• Force

• Power

A light bulb does 100 J of work in 10 seconds. Calculate the power used.

• 110 W

• 10 J

• 10 W

• 90 W

What is the unit for power?

• newtons (N)

• Joules (J)

• meters (m)

• Watts (W)

How do you calculate power?

• Work + time

• Work - time

• Work x time

• Work  $\div$ time

If you increase your work and decrease your time, you will have

• more power

• less power

• same amount of power

• power rating can not be determined

A person weighing 600 N gets on an elevator. The elevator lifts the person 6 m in 10 seconds.  How much power was used?

• 360 W 
• 60 W
• 3600 W
• 600 W

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-2

A construction worker uses a pulley and a rope to raise an 85 kg person to a height of 2 m in 6 s. How much did he do?

• 1,670 J

• 833 J

• 278 J

• 417 J

Tags

NGSS.HS-PS3-1

NGSS.HS-PS2-1

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

A light bulb does 100 J of work in 10 seconds. Calculate the power used.

• 110 W

• 10 J

• 10 W

• 90 W

W = 500 Joules 
t = 25 seconds
P = ???

• 0.05 W
• 20 W
• 12500 W
• 2000 W