Power Problems

Person A and Person B are both using the same amount of work to lift something. Person A takes half as much time to do it. Who has greater power.

• Person A

• Person B

P=25 watts 
W=5000 Joules 
t=???

• 200 sec

• 0.0005 s

• 125000 s

• 125 s

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

What percent energy is wasted by a machine if the energy input is 262 J and the energy output is 131 J?

• 5%

• 50%

• 55%

The dog picked up a big branch onto his mouth in 6 seconds. What is the power of the dog if it has the work of 50 J?

• 8.33 W

• 56 W

• 44 W

• 300 W

Tags

NGSS.MS-PS3-5

A boy was carrying 10 books are once that weights 10kg. He applied a 150N force, so he obtained a distance of 30m in one minute. What is the power of the boy?

• 0 W

• 25 W

• 50 W

• 75 W

Tags

NGSS.MS-PS3-5

The runner applied a 40N force in order for him to speed up from the start. If he traveled 5km after 1 hour, what is his power?

• 0.55

• 5.555

• 55.55

• 555.5

Tags

NGSS.MS-PS2-2

A steel cabinet that weighs 40 kg is lifted by a set of pulleys to height of 15 meters. If the lift happens in 3 minutes, how much power is used. (The acceleration is 9.8m/s²)

• 2.18 W

• 32.67 W

• 3.33 W

• 1960 W

Tags

NGSS.MS-PS3-4

NGSS.MS-PS3-5

Calculating the Power of a runner who consumed 160 J is 40 seconds would give 4 Watts. What will be the power once twice the time is applied?

• 2 W

• 4 W

• 8 W

• 16 W

A horse performs 15000 joules of work pulling a wagon for 20 seconds. What is the horse's power?