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Energy Calculation help

  • Thread starter lovcullen
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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
 

Answers and Replies

  • #2
Redbelly98
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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).
 
  • #3
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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).
Power = Energy x Time
Energy = Power / Time
Time = Power / Energy

Is this right ??
 
  • #4
Redbelly98
Staff Emeritus
Science Advisor
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Not quite, it's

Power = Energy / Time
etc.

Using that, can you find (a) the energy supplied to the 800 W motor?
 
  • #5
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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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