Calculate Time to Lift Piano: 132kg Piano, 7.3m High, 470W Power

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In summary, the piano is being lifted at a steady speed of 7.3m above the ground by a crane with a steady power of 470W. To find the time it takes to lift the piano, we can use the fact that power is the rate at which work is done, and think about what units work is measured in. The equation for KE and PE at the bottom and the top is not equal, as the energy being conserved means that the energy from the point of origin is equal to the energy at its destination. However, the machine is doing work on the system by adding energy.
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mikefitz
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A piano whose mass is 132 kg is being lifted at a steady speed from ground level straight up to an apartment 7.3m above the ground. The crane that is doing the lifting produces a steady power of 470W. How much time does it take to lift the piano?

Sorry for so many topics, I do appreciate the help though!

anyway, I know that the sum of KE and PE on the ground should be equal to KE and PE at the top ..

KEground = .5 * 132 * v^2
PEground = 0

KEtop = .5 * 132 * v^2
PEtop = 9452.916


My question is how do I find the time it takes to lift the piano if I don't know what the velocities are? thanks
 
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  • #2
Perhaps it would be helpful to think of power as the rate at which work is done. Also, think about what units work is measured in.

You mentioned "velocities"... constant velocity; v = v.

Your error is thinking that the sum of the KE and PE at the bottom is the same as the sum of the KE and PE at the top. There's one thing missing from that equation...
 
  • #3
drpizza said:
Your error is thinking that the sum of the KE and PE at the bottom is the same as the sum of the KE and PE at the top. There's one thing missing from that equation...

I thought that energy being conserved meant that the energy from the point of origin was equal to the energy at its destination...since this isn't true I'm unsure as to what I'm missing :confused: ?
 
  • #4
The machine is doing work on the system... i.e. it's adding energy.
 

Related to Calculate Time to Lift Piano: 132kg Piano, 7.3m High, 470W Power

1.

How long will it take to lift a 132kg piano to a height of 7.3m with 470W of power?

The time it takes to lift the piano will depend on several factors, such as the efficiency of the lifting mechanism, the strength and endurance of the person lifting the piano, and any external factors that may affect the lifting process. However, using the given information, we can estimate that it would take approximately 6 seconds to lift the piano to a height of 7.3m with 470W of power.

2.

How much power is needed to lift a 132kg piano to a height of 7.3m in a given amount of time?

The amount of power needed to lift the piano will depend on the time frame in which the lifting needs to be done. However, using the given information, we can estimate that it would require approximately 470W of power to lift the piano to a height of 7.3m in 6 seconds.

3.

What is the maximum height that can be achieved with 470W of power when lifting a 132kg piano?

The maximum height that can be achieved with 470W of power when lifting the piano will depend on several factors, such as the efficiency of the lifting mechanism and the strength of the person lifting the piano. However, using the given information, we can estimate that 470W of power would be sufficient to lift the piano to a height of approximately 7.3m.

4.

How much power is required to lift a piano that weighs more or less than 132kg?

The amount of power required to lift a piano will depend on its weight, as well as the height it needs to be lifted to and the time frame in which the lifting needs to be done. Generally, the heavier the piano, the more power will be needed to lift it.

5.

Can the time it takes to lift the piano be reduced by using more power?

Yes, the time it takes to lift the piano can be reduced by using more power. However, it is important to note that there may be limits to how much power can be used without causing damage to the lifting mechanism or posing a safety risk to the person lifting the piano. It is important to consider all factors and use caution when increasing the power used for lifting.

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