Advertisements
Advertisements
प्रश्न
Figure shows a paddle wheel coupled to a mass of 12 kg through fixed frictionless pulleys. The paddle is immersed in a liquid of heat capacity 4200 J K−1 kept in an adiabatic container. Consider a time interval in which the 12 kg block falls slowly through 70 cm. (a) How much heat is given to the liquid? (b) How much work is done on the liquid? (c) Calculate the rise in the temperature of the liquid neglecting the heat capacity of the container and the paddle.
Advertisements
उत्तर
(a) Heat is not given to the liquid; instead, the mechanical work done is converted to heat. Also the container is adiabatic. So, no heat can enter or exit the system. This implies that the heat given to the liquid is zero.
(b) Since the 12 kg mass falls through a distance of 70 cm under gravity, energy is lost by this mass. As this mass is connected to the paddle wheel, energy lost by this mass is gained by the paddle wheel.
⇒">⇒ Work done on the liquid = PE lost by the 12 kg mass
Now,
PE lost by the 12 kg mass = mgh
= 12 × 10 × 0.70
= 84 J
(c) Suppose ∆t is the rise in temperature of the paddle wheel when the system gains energy.
⇒">⇒ 84 = ms∆t
If s is the specific heat of the system, then
84 = 1 × 4200 × ∆t .........(for 'm' = 1 kg)
\[∆ t = \frac{84}{4200} = \frac{1}{50} = 0 . 02 K\]
APPEARS IN
संबंधित प्रश्न
State two factors upon which the heat absorbed by a body depends
Specific heat capacity of substance A is 3.8 J g-1K-1 whereas the specific heat capacity of substance B is 0.4 J g-1 K-1
(i) Which of the two is a good conductor of heat?
(ii) How is one led to the above conclusion?
(iii) If substances A and B are liquids then which one would be more useful in car radiators?
A heater of power P watt raises the temperature of m kg of a liquid by Δt K in time t s. Express
the specific heat capacity of liquid in terms of above data.
The S.I. unit of specific heat capacity is ______.
Explain the term boiling ?
How much heat energy is released when 5.0 g of water at 20℃ changes into ice at 0℃? Take specific heat capacity of water = 4.2 J g-1 K-1, Specific latent heat of fusion of ice = 336 J g-1.
Name the radiations for which the green house gases are transparent ?
What impact will global warming have on the health of the affected population?
Who shall pay carbon tax ?
A calorimeter has mass 100 g and specific heat 0.1 kcal/ kg °C. It contains 250 gm of liquid at 30°C having specific heat of 0.4 kcal/kg °C. If we drop a piece of ice of mass 10 g at 0°C, What will be the temperature of the mixture?
The specific heat capacity of a body depends on _____________ .
Fill in the following blank using suitable word:
SI unit of heat is .........
A liquid X has specific heat capacity higher than the liquid Y. Which liquid is useful as heat reservoir to keep juice bottles without freezing?
Water boils at 120 °C in a pressure cooker. Explain the reason.
Name the substance which has maximum specific heat capacity.
Write two advantages of high specific heat capacity of water.
Does the specific heat capacity of a substance depend upon its mass and rise in temperature only?
Explain, why do sandy soils, get heated up quickly as compared to wet soils?
Specific heat capacity of substance A is 3.8 J g-1 K-1whereas the specific heat capacity of substance B is 0.4 J g-1 K-1. Which of the two is a good conductor of heat? How is one led to this conclusion?
Write an expression for the heat energy liberated by a hot body.
Describe a method to determine the specific heat capacity of a solid (say, a piece of copper).
Will the value of specific heat’capacity and specific latent heat of a substance change if the scale is °F instead of °C?
The temperature of a lead piece of mass 400 g rises from 20°C to 50°C when 1560 J of heat is supplied to it. Calculate: Heat capacity of lead piece.
A vessel of negligible heat*capacity contains 40g of ice in it at 0°C, 8g of steam at 100°C is passed into the ice to melt it. Find the final temperature of the contents of the vessel.
(Specific latent heat of vaporization of steam = 2268 J/g, specific latent heat of fusion of ice = 336 J/f and specific heat capacity of water = 4.2 J/g°C)
Derive an expression for finding out the specific heat capacity of a body (solid) from the readings of an experiment given below:
(i) Mass of empty calorimeter (with stirrer) = m1 gm
(ii) Mass of the metal piece = M gm
(iii) Mass of colorimeter and water = m2 gm
(iv) Initial temperature and water = t1°C
(v) Temperature of hot solid (metal piece) = t2 °C
(vi) Final temperature of the mixture = t°C
(vii) Specific heat of calorimeter = 0.4 J gm / °C
Solve the following problem.
What is the specific heat of metal if 50 cal of heat is needed to raise 6 kg of the metal from 20°C to 62 °C?
From the options given below the specific heat of _______ is maximum.
Explain how heat capacity of a solid can be determined by the method of mixture.
If 'Cp' and 'Cv' are molar specific heats of an ideal gas at constant pressure and volume respectively. If 'λ' is the ratio of two specific heats and 'R' is universal gas constant then 'Cp' is equal to ______.
The ratio of the specific heats `c_"p"/c_"v"=gamma` in terms of degrees of freedom 'n' is given by ______.
Match the following
| 1. | Specific heat capacity | a. | Dewar bottle |
| 2. | Calorimeter | b. | Lavoisier and Simon |
| 3. | Vacuum flask | c. | J Kg-1 K-1 |
| 4. | Ice – calorimeter | d. | Heat capacity |
Match the columns:
| Column ‘A’ | Column ‘B’ |
| The SI unit of specific heat capacity | (a) Jkg−1°C−1 |
| (b) kg/m3 | |
| (c) calorie |
A geyser heats water flowing at a rate of 2.0 kg per minute from 30°C to 70°C. If the geyser operates on a gas burner, the rate of combustion of fuel will be ______ g min-1.
[Heat of combustion = 8 × 103 Jg-1 Specific heat of water = 4.2 Jg-1°C-1]
A 0.2 kg metal at 150°C is placed in a copper calorimeter (water equivalent 0.025 kg) with 150 cm³ water at 27°C. Final temperature is 40°C. Find the specific heat of the metal.
