Question

If it took you 5 seconds to move a rock 15 meters using a force of 150 Newtons, how much power did you need to use?

500 joules/sec
45 joules/sec
4,500 joules
450 joules/sec

Answer 1

450 joules/sec

Step-by-step explanation:

150 x 15 = 2,250

2,250 / 5 = 450

= 450 joules/sec

Answer 2

Given that:

Time taken = 5 seconds

Distance = 15 meters

Force = 150 Newtons

Power = ?

Recall that power is the rate of work done per unit time

i.e Power = work / time

(since work is a product of force and distance, then

power = (force x distance)/ time

Power = (150 Newtons x 15 m) / 5 s

Power = 2250 / 5

Power = 450 joules per second