Calculating Mass of Water Pumped by a Motor

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Homework Help Overview

The problem involves calculating the mass of water pumped by a motor with a specified power rating, voltage, current, height, and time. The subject area includes concepts from physics related to power, energy, and mechanics.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the relationship between power, current, and voltage, questioning the implications of the motor's power rating versus the calculated power based on the given current and voltage.

Discussion Status

There is an ongoing exploration of the problem's parameters, with some participants suggesting that the motor's efficiency and the potential typo in the power rating should be considered. Multiple interpretations of the motor's power output are being discussed.

Contextual Notes

Participants note a discrepancy between the calculated power (240W) and the motor's rated power (100W), leading to discussions about efficiency and potential errors in the problem statement.

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Homework Statement



A motor,rated 100W,runs from a source voltage 120V.If 2A of current flows through it then calculate the mass of water pumped by it to a height of 10m in 5 seconds.

Homework Equations



P=IV
P=E/t
E=mgh

The Attempt at a Solution


P=IV
P=mgh/t
mgh/t=IV
m=IVt/gh
m=(2)(120)(5)/(9.8)(10)
m=12.24kg.

Is my solution correct and does this question make correct sense?
Thanks.
 
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hacker804 said:

Homework Statement



A motor,rated 100W,runs from a source voltage 120V.If 2A of current flows through it then calculate the mass of water pumped by it to a height of 10m in 5 seconds.

Homework Equations



P=IV
P=E/t
E=mgh

The Attempt at a Solution


P=IV
P=mgh/t
mgh/t=IV
m=IVt/gh
m=(2)(120)(5)/(9.8)(10)
m=12.24kg.

Is my solution correct and does this question make correct sense?
Thanks.

P = V.I formula gives P = 120 x 2 = 240W, yet the motor is rated at 100W.
Could it be that the engine is not perfectly efficient, the rating means a power output is 100W?
The rating of a motor is usually the maximum output of that motor, so the answer might be much smaller, as in (100)(5)/(9.8)(10)
 
No.its 240W.i asked my teacher and he said there was a typo in the question.
 
hacker804 said:
No.its 240W.i asked my teacher and he said there was a typo in the question.

You should tell about the typo then!

Did he say the typo was that the motor was rated at 1000 W?
 
Yup.its actually 240W.i have an older edition of the textbook and its corrected in the newer edition.my teacher checked and told me.
 

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