Calculate Motor Power in kW for 15 Tonnes, 16 m, 0.2 m/s

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Discussion Overview

The discussion revolves around calculating the motor power required to move a 15-tonne load over a distance of 16 meters at a speed of 0.2 m/s. Participants explore the relevant physics concepts, including force, power, and the role of friction in this context.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests using the equation F = m*a to find the force required to move the load.
  • Another participant counters that F = m*a only accounts for the force needed to accelerate the load to the desired speed and emphasizes the importance of overcoming friction.
  • A third participant provides additional context, noting that the load is for a crane trolley moving along beams and inquires about equations that might disregard friction, citing their lecturer's advice.
  • Another response claims that if friction is neglected, no power is needed to maintain constant speed, and discusses the energy required to accelerate the load, linking it to power as energy over time.

Areas of Agreement / Disagreement

Participants express differing views on the significance of friction in the calculations, with some arguing it can be neglected while others assert it must be considered. The discussion remains unresolved regarding the appropriate approach to calculating the required power.

Contextual Notes

There are unresolved assumptions regarding the friction involved in the system, as well as the conditions under which power calculations are made. The discussion also reflects varying interpretations of the physical principles involved.

enginecadet88
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Homework Statement



Ok so i need to choose a motor that is capable of moving 15 tonnes (metric) over a distance of 16 m at 0.2 m/s.

So, I am guessing i need to first find the force required to move this object which would be F=m*a. Is this right?

Now, what would be the equation to find the power required in Kw?


Homework Equations





The Attempt at a Solution

 
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No, f=ma is only the force needed to accelerate it upto 0.2m/s
The power is mainly to overcome friction.
You need to know what friction is involved, consider how hard it is to drag a 15tn rock over concrete compared to how much power you need to pull a 15tn boat.
 
Ill give some more background. The calculations i need really don't have to go into too much detail though.

This equation is for a crane trolley of 15 tonnes (metric) which moves along 2 beams. So, it is not a metal on metal contact. It will be a set of wheels or more accurately a rack and pinion set. Are there equations which do not take friction into account as i have been told by my lecturer that friction can be disregard.
 
Neglecting friction it takes no power to keep the trolley moving at any speed.
To get it moving you have to put in energy = 1/2 m V^2, how quickly you do this (ie how long you take to accelerte it ) determines the power (power is energy/time)
 

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