Considering a household refrigerator as a reversible engine opera… - Vidyadip

Question

Considering a household refrigerator as a reversible engine operating between the melting point of ice and room temperature $27^{\circ} C$, estimate the energy provided joules ( $J$ ) to freeze 1 kg of water, the temperature of water is given in $0^{\circ} C , L = 8 0 Cal g ^{-1}$.

✓

Answer

Given that :
$\begin{aligned}T_1 & =27+273=300 K \\T_2 & =0+273=273 K \\m & =1 kg=1000 g, L=80 calg^{-1} \\\text { Melting energy } \quad Q_2 & =m \times L \\& =1000 \times 80 cal=8 \times 10^4 cal\end{aligned}$
Using the relation
$\begin{aligned}\frac{Q_1}{Q_2} & =\frac{T_1}{T_2} \\Q_1 & =\left(\frac{T_1}{T_2}\right) \times Q_2=\frac{300}{273} \times 8 \times 10^4 \\& =8.79 \times 10^4\end{aligned}$
Desired deliverable energy
$\begin{aligned}W & =Q_1-Q_2 \\W & =8.79 \times 10^4-8 \times 10^4 \\& =0.79 \times 10^4 cal \\& =7.9 Kcal .\end{aligned}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "2 Marks Questions" from PART - 2 CH - 11 Thermodynamics→PART - 2 CH - 11 Thermodynamics — all question types→Physics STD 11 Science question papers→Gujarat Board STD 11 Science question papers→Gujarat Board question paper generator→

Similar questions

Write an expression for the moment of inertia of a circular disc of mass $M$ and radius $R.$

About an axis passing through its centre, and perpendicular to its plane.
About its diameter.
About a tangent to its own plane.
About a tangent perpendicular to the plane of the disc.

Consider an ice cube of edge 1.0cm kept in a gravity free hall. Find the surface area of the water when the ice melts. Neglect the difference in densities of ice and water.

If two masses $m_1$ and $m_2$ are kept at a distance, what will be the position of their center of mass?

Give an example of achievement in unification.

Calculate the percentage increase in length of a wire of diameter 2.5mm stretched by a force of 100kg weight. Young's modulus of elasticity of wire is $12.5 \times 10^{11}$ dyne/ sq cm.

Draw a graph from the following data. Draw tangents at $x = 2, 4, 6$ and $8$. Find the slopes of these tangents. Verify that the curve drawn is $y = 2x^2$ and the slope of dy tangent is $\tan\theta=\frac{\text{dy}}{\text{dx}}=4\text{x}.$

x	1	2	3	4	5	6	7	8	9	10
y	2	8	18	32	50	72	98	128	162	200

What are the limitations of the first law of thermodynamics?

Draw p-V diagram of a Carnot cycle.

A long narrow horizontal slit is placed 1mm above a horizontal plane mirror. The interference between the light coming directly from the slit and that after reflection is seen on a screen 1.0m away from the slit. Find the fringe-width if the light used has a wavelength of 700nm.

A glass ball of radius 4 mm is released into the sea. It starts moving with a velocity of 52.3 $m / sec$. If the density of sea water is $1.015 \times 10^3 kg /$ $m ^3$ then what will be the value of the viscous force acting on the bullet? Find out coefficient of viscosity of sea water $=0.01$ Poise.