Question(Physics 20) about Power(watts)

  • Thread starter Jyote25
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In summary, the conversation discusses the calculation of the power output of an electric motor that is pulling an elevator at a constant velocity. The formula for power (P=W/t) is mentioned, along with the equations for force (F=ma), velocity (v=d/t), and acceleration (a=v/t). The conversation also mentions that acceleration is zero and that work and time are needed to find power, but the time is not known. A hint is given to use a formula for power that involves force instead of work.
  • #1
Jyote25
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Homework Statement



An 8.5x102 elevator (including occupants) is pulled up at a constant velocity of 1.00 m/s by an electric motor. Calculate the power output of the electric motor.


Homework Equations



P=W/t

F=ma

v=d/t

a=v/t

The Attempt at a Solution




Having trouble figuring out what the acceleration and time are in order to find force times distance(Work)

Thank you for your help!
 
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  • #2
Hi Jyote25! :smile:
Jyote25 said:
An 8.5x102 elevator (including occupants) is pulled up at a constant velocity …

Having trouble figuring out what the acceleration and time are in order to find force times distance(Work)

acceleration is zero

time of what? :confused:
 
  • #3
Is time really needed to solve this equation? I guess not since we've already figured out that Acceleration is zero. But in order to find work we still need distance...ideas?
 
  • #4
Jyote25 said:
Is time really needed to solve this equation? I guess not since we've already figured out that Acceleration is zero. But in order to find work we still need distance...ideas?

very true :smile:

but who asked you for the work? :confused:
 
  • #5
Well, in order to find Power we need work to find Joules/second, which equates to a Watt, which is going to be the 'power output' of the motor. P=W/t
 
  • #6
yeeees … well, since you don't know the work and you don't know the time, that's a teeny bit unhelpful! :biggrin:

hint: do you know any formula for power that involves force instead of work? :wink:
 

1. What is power and how is it measured?

Power is the rate at which energy is transferred or work is done. It is measured in watts (W), which is equal to one joule per second.

2. How is power related to energy and time?

Power is directly proportional to both energy and time. This means that the higher the power, the more energy is transferred or work is done in a given amount of time.

3. Can power be negative?

Yes, power can be negative. This occurs when the direction of energy transfer or work done is opposite to the direction of the power. For example, when a car brakes, it has negative power as it is using energy to slow down.

4. What is the difference between mechanical power and electrical power?

Mechanical power is the rate at which work is done by a mechanical system, while electrical power is the rate at which electrical energy is transferred or work is done by an electrical system.

5. How can power be calculated?

Power can be calculated using the formula P = W/t, where P is power in watts, W is work done in joules, and t is time in seconds. It can also be calculated using the formula P = V x I, where V is voltage in volts and I is current in amperes.

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