Heat And Thermodynamics - Mechanics - Physics Previous Year Questions

1

2024 · Physics · Mechanics · Heat And Thermodynamics

TG EAPCET 2024 ONLINE 10TH MAY EVENING SHIFT

The temperature at which the rms speed of oxygen molecules is $75 \%$ or rms speed of nitrogen molecules at a temperature of $287^{\circ} \mathrm{C}$

A

$87^{\circ} \mathrm{C}$

B

$127^{\circ} \mathrm{C}$

C

$227^{\circ} \mathrm{C}$

D

$360^{\circ} \mathrm{C}$

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2

2024 · Physics · Mechanics · Heat And Thermodynamics

TG EAPCET 2024 ONLINE 10TH MAY EVENING SHIFT

When $Q_{1}$ amount of heat supplied to a monoatomic gas, the work done by the gas is $W$. When $Q_{2}$ amount of heat is supplied to a diatomic gas, the work done by the gas is $2 W$. Then, $Q_{1}: Q_{2}$.

A

$2: 3$

B

$3: 5$

C

$5: 7$

D

$5: 14$

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3

2024 · Physics · Mechanics · Heat And Thermodynamics

TG EAPCET 2024 ONLINE 10TH MAY EVENING SHIFT

Steam of mass 60 g at a temperature $100^{\circ} \mathrm{C}$ is mixed with water of mass 360 g at a temperature $40^{\circ} \mathrm{C}$. The ratio of the masses of steam and water in equilibrium is (Latent heat of steam is $540 \mathrm{cal} \mathrm{g}^{-1}$ and specific heat capacity of water is $1 \mathrm{cal} \mathrm{g}^{-1}{ }^{\circ} \mathrm{C}^{-1}$ )

A

$1: 20$

B

$1: 10$

C

$1: 5$

D

$1: 3$

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4

2024 · Physics · Mechanics · Heat And Thermodynamics

TG EAPCET 2024 ONLINE 10TH MAY EVENING SHIFT

The temperature difference between the ends of two cylindrical rods $A$ and $B$ of the same material is $2: 3$. In steady state the ratio of the rates of flow of heat through the rods $A$ and $B$ is $5: 9$. If the radii of the rods $A$ and $B$ are in the ratio $1: 2$, then the ratio of lengths of the rods $A$ and $B$ is

A

$2: 7$

B

$3: 7$

C

$2: 5$

D

$3: 10$

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5

2024 · Physics · Mechanics · Heat And Thermodynamics

TG EAPCET 2024 ONLINE 10TH MAY MORNING SHIFT

A big liquid drop splits into $n$ similar small drops under isothermal conditions, then in the process

A

volume decreases

B

total surfaces area decrease

C

energy is absorbed

D

energy is liberated

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6

2024 · Physics · Mechanics · Heat And Thermodynamics

TG EAPCET 2024 ONLINE 10TH MAY MORNING SHIFT

A vessel contains hydrogen and nitrogen gases in the ratio $2: 3$ by mass. If the temperature of the mixture of the gases is $30^{\circ} \mathrm{C}$, then the ratio of the average kinetic energies per molecule of hydrogen and nitrogen gases is (Molecular mass of hydrogen $=2$ and molecular mass of nitrogen $=28$ )

A

$3: 7$

B

$2: 3$

C

$1: 1$

D

$1: 14$

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7

2024 · Physics · Mechanics · Heat And Thermodynamics

TG EAPCET 2024 ONLINE 10TH MAY MORNING SHIFT

37 g of ice at $0^{\circ} \mathrm{C}$ temperature is mixed with 74 g of water at $70^{\circ} \mathrm{C}$ temperature. The resultant temperature is (specific heat capacity of water $=1 \mathrm{cal} {\mathrm{g}^{-1o}} \mathrm{C}^{-1}$ and latent heat of fusion of ice $=80 \mathrm{cal} \mathrm{g}^{-1}$ )

A

$45^{\circ} \mathrm{C}$

B

$70^{\circ} \mathrm{C}$

C

$20^{\circ} \mathrm{C}$

D

$35^{\circ} \mathrm{C}$

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8

2024 · Physics · Mechanics · Heat And Thermodynamics

TG EAPCET 2024 ONLINE 10TH MAY MORNING SHIFT

The ratio of the specific heat capacities of a gas is 1.5 . When the gas undergoes adiabatic process, its volume is doubled and pressure becomes $p_1$. When the gas undergoes isothermal process, its volume is doubled and pressure becomes $p_2$. If $p_1=p_2$, the ratio of the initial pressures of the gas when it undergoes adiabatic and isothermal processes is

A

$\sqrt{3}: \sqrt{2}$

B

$1: 1$

C

$\sqrt{3}: 1$

D

$\sqrt{2}: 1$

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9

2024 · Physics · Mechanics · Heat And Thermodynamics

TG EAPCET 2024 ONLINE 10TH MAY MORNING SHIFT

The thickness of a uniform rectangular metal plate is 5 mm and the area of each surface is $5 \mathrm{~cm}^5$. In steady state, the temperature difference between the two surfaces of the plate is $14^{\circ} \mathrm{C}$. If the heat flowing through the plate in one second from one surface to the other surface is 42 J , then the thermal conductivity of the metal is

A

$90 \mathrm{Wm}^{-1} \mathrm{~K}^{-1}$

B

$30 \mathrm{Wm}^{-1} \mathrm{~K}^{-1}$

C

$45 \mathrm{Wm}^{-1} \mathrm{~K}^{-1}$

D

$60 \mathrm{Wm}^{-1} \mathrm{~K}^{-1}$

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10

2024 · Physics · Mechanics · Heat And Thermodynamics

TG EAPCET 2024 ONLINE 11TH MAY MORNING SHIFT

A liquid cools from a temperature of 368 K to 358 K in 22 min . In the same room, the same liquid takes 12.5 min to cool from 358 K to 353 K . The room temperature is

A

$27.5^{\circ} \mathrm{C}$

B

27.5 K

C

$30.5^{\circ} \mathrm{C}$

D

30.5 K

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11

2024 · Physics · Mechanics · Heat And Thermodynamics

TG EAPCET 2024 ONLINE 11TH MAY MORNING SHIFT

For a gas in a thermodynamic process, the relation between internal energy $U$, the pressure $p$ and the volume $V$ is $U=3+15 p V$. The ratio of the specific heat capacities of the gas at constant volume and constant pressure is

A

$\frac{5}{3}$

B

$\frac{3}{5}$

C

$\frac{4}{3}$

D

$\frac{3}{4}$

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12

2024 · Physics · Mechanics · Heat And Thermodynamics

TG EAPCET 2024 ONLINE 11TH MAY MORNING SHIFT

A pendulum clock loses 10.8 s a day when the temperature is $38^{\circ} \mathrm{C}$ and gains 108 s a day when the temperature is $18^{\circ} \mathrm{C}$. The coefficient of linear expansion of the metal of the pendulum clock is

A

$7 \times 10^{-5}{ }^{\circ} \mathrm{C}^{-1}$

B

$1.25 \times 10^{-5}{ }^{\circ} \mathrm{C}^{-1}$

C

$5 \times 10^{-5}{ }^{\circ} \mathrm{C}^{-1}$

D

$2.5 \times 10^{-5}{ }^{\circ} \mathrm{C}^{-1}$

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13

2024 · Physics · Mechanics · Heat And Thermodynamics

TG EAPCET 2024 ONLINE 11TH MAY MORNING SHIFT

At a pressure $p$ and temperature $127^{\circ} \mathrm{C}$, a vessel contains 21 g of a gas. A small hole is made into the vessel, so that the gas in it leaks out. At a pressure of $\frac{2 p}{3}$ and a temperature of $t^{\circ} \mathrm{C}$, the mass of the gas leaked out is 5 g . Then, $t=$

A

$273{ }^{\circ} \mathrm{C}$

B

$77^{\circ} \mathrm{C}$

C

$350^{\circ} \mathrm{C}$

D

$87^{\circ} \mathrm{C}$

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14

2024 · Physics · Mechanics · Heat And Thermodynamics

TG EAPCET 2024 ONLINE 9TH MAY EVENING SHIFT

A solid sphere at a temperature $T \mathrm{~K}$ is cut in to two hemisphere. The ratio of energies radiated by one hemisphere to the whole sphere per second is

A

$1: 1$

B

$1: 2$

C

$3: 4$

D

$1: 4$

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15

2024 · Physics · Mechanics · Heat And Thermodynamics

TG EAPCET 2024 ONLINE 9TH MAY EVENING SHIFT

When 54 g of ice at $-20^{\circ} \mathrm{C}$ is mixed with 25 g of steam at $100^{\circ} \mathrm{C}$, then the final mixture at thermal equilibrium contains

A

20 g water at $100^{\circ} \mathrm{C}$

B

73 g water at $100^{\circ} \mathrm{C}$ and 6 g steam at $100^{\circ} \mathrm{C}$

C

8 g steam at $100^{\circ} \mathrm{C}$ and 12 g water at $0^{\circ} \mathrm{C}$

D

20 g water at $50^{\circ} \mathrm{C}$

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16

2024 · Physics · Mechanics · Heat And Thermodynamics

TG EAPCET 2024 ONLINE 9TH MAY EVENING SHIFT

If $d Q, d U$ and $d W$ are heat energy absorbed, change in internal energy and external work done respectively by a diatomic gas at constant pressure, then $d W: d U: d Q$ is

A

$5: 3: 2$

B

$7: 5: 2$

C

$4: 3: 1$

D

$2: 5: 7$

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17

2024 · Physics · Mechanics · Heat And Thermodynamics

TG EAPCET 2024 ONLINE 9TH MAY EVENING SHIFT

If the temperature of a gas increased from $27^{\circ} \mathrm{C}$ to $159^{\circ} \mathrm{C}$, the increase in the rms speed of the gas molecules is

A

$142 \%$

B

$71 \%$

C

$80 \%$

D

$20 \%$

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18

2025 · Physics · Mechanics · Heat And Thermodynamics

TG EAPCET 2025 ONLINE 2ND MAY EVENING SHIFT

A body cools from a temperature of $60^{\circ} \mathrm{C}$ to $50^{\circ} \mathrm{C}$ in 10 minutes and $50^{\circ} \mathrm{C}$ to $40^{\circ} \mathrm{C}$ in 15 minutes. The time taken in minutes for the body to cool from $40^{\circ} \mathrm{C}$ to $30^{\circ} \mathrm{C}$ is

A

30

B

20

C

25

D

40

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19

2025 · Physics · Mechanics · Heat And Thermodynamics

TG EAPCET 2025 ONLINE 2ND MAY EVENING SHIFT

When the temperature of a gas in a closed vessel is increased by $2.4^{\circ} \mathrm{C}$, its pressure increases by $0.5 \%$. The initial temperature of the gas is

A

$120^{\circ} \mathrm{C}$

B

$240^{\circ} \mathrm{C}$

C

$480^{\circ} \mathrm{C}$

D

$207^{\circ} \mathrm{C}$

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20

2025 · Physics · Mechanics · Heat And Thermodynamics

TG EAPCET 2025 ONLINE 2ND MAY EVENING SHIFT

A gas is suddenly compressed such that its absolute temperature is doubled. If the ratio of the specific heat capacities of the gas is 1.5 , then the percentage decrease in the volume of the gas is

A

30

B

50

C

25

D

75

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