How long will it take a 500 watt electric motor to do 1.5 x10^5 j of work

Power = (work) divided by (time to do the work)

500 joule/sec = (1.5 x 10⁵ J) / (time)

Multiply each side

by time: (time) x (500 joule/sec) = 1.5 x 10⁵ J

Divide each side

by 500 J/sec: Time = (1.5 x 10⁵ J) / (500 J/sec)

= (1.5 x 10⁵ / 500) (J-sec/J)

= 300 sec

= 5 minutes.