
#1
May512, 05:14 PM

P: 6

Power to lift* a piano
A piano of mass 200 kg is lifted vertically by a 0.5 hp motor. Given that 746 watt = 1 hp, how long will it take the motor to lift the piano to an apartment that is 20 m above the ground? Not really sure how to start this question, so any explanation would be greatly appreciated. 



#2
May512, 05:58 PM

P: 45

1 watt = 1 joule of energy / 1 second
And has you lift the piano you are doing work ( in Joules ) to raise the piano against the Earth's gravity so now you have a connection between time ( what you are looking for ) and the energy involved in lifting the piano. A free body diagram might help you as well to visualize. (i.e. draw a picture including ALL of the forces acting on the piano). Have fun! 



#3
May512, 06:03 PM

P: 6

ooh ok, I didn't realize that 1 watt = 1 joule per second, that helped out quite a bit. Thanks so much for the response!



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