What maximum power must the motor provide?

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Homework Help Overview

The problem involves a loaded ore car with a mass of 950 kg being pulled up an inclined mine shaft at a constant speed after an initial acceleration. The discussion focuses on calculating the power required by the winch motor during different phases of the car's movement.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the relationship between force, power, and work done, with some attempting to derive the necessary power using the mass, acceleration, and distance. Questions arise regarding the calculation of distance and the force exerted by the cable.

Discussion Status

The discussion is ongoing, with participants exploring different aspects of the problem. Some have provided hints and guidance regarding the relationship between force and power, while others express uncertainty about specific calculations and the pulling force required.

Contextual Notes

Participants are working under the constraints of the problem's parameters, including the mass of the ore car, the incline of the shaft, and the time taken to reach a certain speed. There is a lack of consensus on how to calculate the pulling force and its implications for power.

stupif
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1. A loaded ore car has a mass of 950 kg and rolls on rails with negligible friction. It starts from rest
and is pulled up a mine shaft by a cable connected to a winch. The shaft is inclined at 30.0°
above the horizontal. The car accelerates uniformly to a speed of 2.20 m/s in 12.0 s and then
continues at constant speed. (a) What power must the winch motor provide when the car is
moving at constant speed? (b) What maximum power must the motor provide? (c) What total
energy transfers out of the motor by work by the time the car moves off the end of the track,
which is of length 1 250 m?
( Ans : (a) 10.2 kW (b) 10.6 kW (c) 5.82 MJ )

2，power = (mass x acceleration x distance)/ time
= (950kg x (2.2/12=0.183m/s^2) x distance )/ 12s

how to find the distance??



The Attempt at a Solution

 
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I'm not sure which part you are attempting to solve. Starting with part a, what's the force exerted by the cable? What power must it exert?
 


i am finding this answer (a) What power must the winch motor provide when the car is
moving at constant speed?
 


So answer my question: What force is exerted by the cable? And how does force relate to power?
 


pulling force...power = workdone / time, workdone = force x distance
 


stupif said:
pulling force...power = workdone / time, workdone = force x distance
OK, so what's the pulling force?
 


dont know
 


stupif said:
dont know
You'll have to figure it out. Hint: constant speed.
 

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