Question

A 345kg piano is lifted 15.0m to the second story of a building. If a crane can do the work in 32.0 s, how much power does the crane exert?

Answer 1

I get `1585` watts to the nearest whole number.

Explanation:

Well, power is defined through the equation,

`P=W/t`

where `W` is the work done in joules, and `t` is the time in seconds.

Work is defined by the equation:

`W=F*d`

where `F` is the force in newtons, and `d` is the distance in meters.

In here, the force exerted will be the weight of the piano, which is

`345 \ "kg"*9.8 \ "m/s"^2=3381 \ "N"`

So, the work is `3381 \ "N"*15 \ "m"=50715 \ "J"`.

The power is then `(50715 \ "J")/(32 \ "s")~~1585 \ "W"`.