How Can I Calculate Energy and Power for an 800W Electric Motor?

AI Thread Summary
To calculate energy and power for an 800W electric motor, the key equations relate power, energy, and time, specifically Power = Energy / Time. The motor raises a load, gaining 24,000 J of gravitational potential energy in 120 seconds. To find the electrical energy supplied to the motor, one must use the power rating and time, while also calculating energy wasted and output power. Efficiency can then be determined by comparing useful output energy to input energy. Understanding these relationships is crucial for solving the problem effectively.
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Energy Calculation ~~help

Homework Statement


Question )
An 800W electric motor is used to raise a load. In 120s, the load gains
24,000 J of gravitational potential energy from the motor
Calculate :
a) electrical energy supplied to the motor
b) energy wasted by the motor
c) output power of the motor
d) efficiency of the motor


Homework Equations


W=J/s


The Attempt at a Solution


I have no idea //

i've got a big school exam next Monday T-T
help me~
thank you
 
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Welcome to Physics Forums.

What is the equation that relates power, energy, and time?

You'll have to show an attempt at solving the problem before getting help (sorry, but that's our policy).
 


Redbelly98 said:
Welcome to Physics Forums.

What is the equation that relates power, energy, and time?

You'll have to show an attempt at solving the problem before getting help (sorry, but that's our policy).

Power = Energy x Time
Energy = Power / Time
Time = Power / Energy

Is this right ??
 


Not quite, it's

Power = Energy / Time
etc.

Using that, can you find (a) the energy supplied to the 800 W motor?
 


Redbelly98 said:
Not quite, it's

Power = Energy / Time
etc.

Using that, can you find (a) the energy supplied to the 800 W motor?

AH~~~~~
now i got it ~:D thank you
 

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