# Help with simple Mechanical question

• Jun 19th 2010, 03:16 AM
peo1987
Help with simple Mechanical question
Hi, thanks to anyone who can help me with this and im sure the answer is staring at me in the face!

My problem is this

I have a Motor rated at 189.19kw and a height of 45m the motor lifts the mass in a time of 3mins.

what is the mass? Its the formula im looking for mainly so please dont just post the answer as i already know what the answer is... thanks for your help
• Jun 19th 2010, 04:04 AM
Failure
Quote:

Originally Posted by peo1987
Hi, thanks to anyone who can help me with this and im sure the answer is staring at me in the face!

My problem is this

I have a Motor rated at 189.19kw and a height of 45m the motor lifts the mass in a time of 3mins.

what is the mass? Its the formula im looking for mainly so please dont just post the answer as i already know what the answer is... thanks for your help

Warning: I'm no physicist, so take my reply with a grain of salt. That said, the way I see it is this:

The average power that is needed to lift a mass $m$ up by $\Delta h$ in the time $\Delta t$ is
$\overline{P}=\frac{\Delta W}{\Delta t}=\frac{mg\Delta h}{\Delta t}$.
If you now assume that $\overline{P}$ is equal to the power that that motor can deliver, you can simply solve $\overline{P}=\frac{mg\Delta h}{\Delta t}$ for $m$.