Question

A crane lifts an I-beam up the side of a building. The crane's power output is 1750W for 20 seconds. After 20 seconds the I-beam was moving at 2 m/s and the mass has 200 kg. Use the work-energy process to determine the change in height of the I-beam.​

Answer 1

Explanation:

This is one of those great problems that is harder to read than to solve!

Remember the following...

Power is the amount of work done over time. $P = \frac{W}{t}$

and that work is Force times distance. $W = F * d$

and that Force is just mass times acceleration. $F = m * a$

So... nesting all the equations together we might get something that looks like. $P = \frac{m*a*d}{t}$

We know the power, the time, the acceleration (at this given time) and the mass. We can then solve for d. $d = \frac{P*t}{m*a}$

Plug and chug!