In some of Joule’s experiments (Figure 1), work was done on water held in an adiabatic calorimeter. The work was done by a rotating paddle, driven by falling weights. Assume the volume of the water remains constant during these experiments.a. In one experiment a 25-kg mass was allowed to fall 20 times through a height of 2 m; what was the maximum amount of work done? b. If a 25-kg mass were fired into the calorimeter and brought to a standstill, what should its initial velocity be to accomplish the same effect as in (a)? c. If the calorimeter held 1.2 kg of water and if process (a) caused the water temperature to rise from 288 to 290 K, what is the numerical value for the factor that connects temperature rise to work under these conditions? Joule's experiment explained:In 1844-1854 the English scientist J. P. Joule conducted experimentswhich were destined to play an important role in science. The objectiveof Joule's experiment was to establish a relation between the amountof work spent to bring about the liberation of heat and the amount ofthe heat liberated. The layout of Joule's experiment was as follows (Fig.1). Paddle wheel 2 was submerged in the heat-insulated vessel 1 to thewalls of which vanes 3 were fastened, the vanes interfering with themotion of water due to rotation of the paddle. Rotation is imparted tothe paddle (stirrer) by the falling load 4 of weight G, connected to thepaddle by means of a rope and pulley 5. As the weight falls through adistance Ah, the work done by it (and, consequently, by the stirrer) isequal to the decrease in the potential energy of the weight GAh. Thewater is churned but not allowed to rotate due to fixed vanes, and theGAh1potential energy of the falling weights is converted into kinetic energyof paddles. Due to friction offered by paddles KE is changed into heatand as a result of it, the temperature of the water in the calorimeterrises. The rise in temperature is measured by an accurate thermometerT inserted in the calorimeter. The process is rapidly repeated severaltimes, such that there is an accurately measurable rise in thetemperature of water.Figure 1- Joule's experiment.

Energy generated by falling is the conversion of potetial energy into kinetic energy whcih is…

Answered: In some of Joule’s experiments (Figure…

Introduction to Chemical Engineering Thermodynamics

8th Edition

ISBN:9781259696527

Author:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart

Publisher:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart

Chapter1: Introduction

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In some of Joule’s experiments (Figure 1), work was done on water held in an adiabatic calorimeter. The work was done by a rotating paddle, driven by falling weights. Assume the volume of the water remains constant during these experiments.
a. In one experiment a 25-kg mass was allowed to fall 20 times through a height of 2 m; what was the maximum amount of work done?
b. If a 25-kg mass were fired into the calorimeter and brought to a standstill, what should its initial velocity be to accomplish the same effect as in (a)?
c. If the calorimeter held 1.2 kg of water and if process (a) caused the water temperature to rise from 288 to 290 K, what is the numerical value for the factor that connects temperature rise to work under these conditions?

Joule's experiment explained:
In 1844-1854 the English scientist J. P. Joule conducted experiments
which were destined to play an important role in science. The objective
of Joule's experiment was to establish a relation between the amount
of work spent to bring about the liberation of heat and the amount of
the heat liberated. The layout of Joule's experiment was as follows (Fig.
1). Paddle wheel 2 was submerged in the heat-insulated vessel 1 to the
walls of which vanes 3 were fastened, the vanes interfering with the
motion of water due to rotation of the paddle. Rotation is imparted to
the paddle (stirrer) by the falling load 4 of weight G, connected to the
paddle by means of a rope and pulley 5. As the weight falls through a
distance Ah, the work done by it (and, consequently, by the stirrer) is
equal to the decrease in the potential energy of the weight GAh. The
water is churned but not allowed to rotate due to fixed vanes, and the
G
Ah
1
potential energy of the falling weights is converted into kinetic energy
of paddles. Due to friction offered by paddles KE is changed into heat
and as a result of it, the temperature of the water in the calorimeter
rises. The rise in temperature is measured by an accurate thermometer
T inserted in the calorimeter. The process is rapidly repeated several
times, such that there is an accurately measurable rise in the
temperature of water.
Figure 1- Joule's experiment.

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