What Mass Should Be Used in Joule's Experiment to Deliver 1.00 kcal?

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Homework Help Overview

The discussion revolves around a physics experiment involving Joule's apparatus, where a mass descends to deliver a specific amount of energy (1.00 kcal) to water. The problem is set within the context of gravitational potential energy and requires determining the appropriate mass to achieve this energy transfer.

Discussion Character

  • Exploratory, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the calculation of mass using the formula for potential energy, questioning the conversion of kcal to joules and the application of the formula U=mg(delta)h. Some participants verify the calculations and unit consistency.

Discussion Status

The discussion is active, with participants confirming the correctness of the original poster's calculations and providing additional insights on unit conversions and formula application. There is a collaborative effort to ensure understanding of the concepts involved.

Contextual Notes

Participants are working under the assumption that the conversion from kcal to joules is accurate and are focused on the implications of using different mass values in the context of the experiment.

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Homework Statement



An experiment is conducted with a basic Joule apparatus, where a mass is allowed to descend by 1.23 m and rotate paddles within an insulated container of water. There are several different sizes of descending masses to choose among. If the investigator wishes to deliver 1.00 kcal to the water within the insulated container after 30.0 descents, what descending mass value should be used? Let g = 9.80 m/s2. (need answer is in kg)

Homework Equations



U=mg(delta)h

The Attempt at a Solution



1kcal=m(9.8)*30*1.23
4186 =m(361.62)
4186/361.62=m
11.576=m


Did I do this correctly?

Thanks in advance.
 
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^ assuming your conversion of kcal to joules is correct that seems like a model solution to me.
 
1 Kcal = 4186 joules
As you say potential energy = mgh
Rememebr to put the units in:

E = m g h
4186 J = m kg * 9.81 m/s^2 * (30*1.23)m
Check units, J = N m = kg m/s^2 m

so m = 4186 / (9.8 * 30 * 1.23) = 11.57kg
 
Thanks for the reminder!
 

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