Calculate Efficiency of Motor Lifting 0.050kg Block at 0.40m/s

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Homework Help Overview

The discussion revolves around calculating the efficiency of a motor lifting a block with a specified mass and velocity. The motor operates at a given current and voltage, prompting participants to explore the relationship between electrical power and mechanical energy in this context.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants discuss the calculation of electrical power and kinetic energy, questioning how to relate these to the efficiency of the motor. There are inquiries about the relevance of kinetic energy and gravitational potential energy in the context of the problem.

Discussion Status

There is ongoing exploration of different interpretations regarding the energy transformations involved. Some participants suggest focusing on gravitational potential energy rather than kinetic energy, while others express confusion about the calculations and assumptions being made.

Contextual Notes

Participants note the absence of height in the problem setup, which complicates the discussion of gravitational potential energy. There is also mention of the need to consider the time taken to lift the mass in relation to power calculations.

  • #31
malemdk said:
Rate of change of potential energy d(mgh)/dt =mg dh/dt = mg x v = Fx v = power needed to maintain the constant velocity, where from you can find efficiency if you know the input power
The fact that you used d(mgh)/dt confuses me, since we don't do that, and you put it on one line.
 
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  • #32
sorry
 
  • #33
TomHart said:
Just one minor issue. The voltage was 3.0 V.
yes
 
  • #34
IDK10 said:
The fact that you used d(mgh)/dt confuses me, since we don't do that, and you put it on one line.
Are you familiar with the equation Power = Force x Velocity?
 
  • #35
Yes , I designed many ,many machines using this equation .
it can be derived from Newtons second law
 
  • #36
malemdk said:
Yes , I designed many ,many machines using this equation .
I was asking @IDK10. He seemed to be having trouble understanding your solution.
 
  • #37
ok
 

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