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Calculate the minimum amount of energy, in joules, required to completely melt $85.0 g$ of silver initially at $15.0 ° C$ . [Given for silver, specific heat capacity $s = 236 J {kg}^{- 1} k^{- 1}$ , and latent heat of fusion $L = 105000 J {kg}^{- 1}$ , melting point $= 1235 K$ ]

Important Questions on Temperature, Heat, and the First Law of Thermodynamics

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JEE Main

IMPORTANT

Principles Of Physics International Student Version>Chapter 18 - Temperature, Heat, and the First Law of Thermodynamics>Problems>Q 24

A solid cylinder of radius

r_{1} = 2.5 cm,

length

h_{1} = 5.5 cm,

emissivity

0.85

and temperature

30 ° C

is suspended in an environment of temperature

50 ° C

(a)

What is the cylinder's net thermal radiation transfer rate

P_{1} ?

(b)

If the cylinder is stretched until its radius is

r_{2} = 0.50 cm

, its net thermal radiation transfer rate becomes

P_{2}

. What is the ratio

P_{2} / P_{1} ?

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Principles Of Physics International Student Version>Chapter 18 - Temperature, Heat, and the First Law of Thermodynamics>Problems>Q 25

A gas within a closed chamber undergoes, the cycle shown in the $P ‐ V$ diagram. The horizontal scale is set by $V_{s} = 4.0 m^{3}$ . Calculate the net energy added to the system as a heat during one complete cycle.

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Principles Of Physics International Student Version>Chapter 18 - Temperature, Heat, and the First Law of Thermodynamics>Problems>Q 26

Two constant-volume gas thermometers are assembled, one with Nitrogen and the other with Hydrogen. Both contain enough gas so that $p_{3} = 78 kPa$ .
(a) What is the difference between the pressures in the two thermometers if both the bulbs are in boiling water?
(b) Which gas is at higher pressure?

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Principles Of Physics International Student Version>Chapter 18 - Temperature, Heat, and the First Law of Thermodynamics>Problems>Q 27

Figure shows (in cross-section) a wall consisting of four layers, with thermal conductivities $k_{1} = 0.060 W m^{- 1} K^{- 1}, k_{3} = 0.040$ $W m^{- 1} K^{- 1}$ and $k_{4} = 0.12 W m^{- 1} K^{- 1} (k_{2}$ is not known). The layer thicknesses are $L_{1} = 1.2 cm, L_{3} = 5.6 cm$ and $L_{4} = 4.0 cm (L_{2}$ is not known). The known temperatures are $T_{1} = 30 ° C, T_{2} = 25 ° C$ and $T_{4} = - 10 ° C$ . Energy transfer through the wall is steady. What is interface temperature $T_{34} ?$

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Principles Of Physics International Student Version>Chapter 18 - Temperature, Heat, and the First Law of Thermodynamics>Problems>Q 28

On a linear

X

temperature scale, water freezes at

- 125.0 ° X

and boils at

360.0 ° X

. On a linear

Y

temperature scale, water freezes at

- 70.00 ° Y

and boils at

- 30.00 ° Y

. A temperature of

50.00 ° Y

corresponds to what temperature on the

X

scale?

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Principles Of Physics International Student Version>Chapter 18 - Temperature, Heat, and the First Law of Thermodynamics>Problems>Q 29

A sphere of radius

0.350 m,

temperature

27.0 ° C

and emissivity is

0.850

is located in an environment of temperature

77.0 ° C

. At what rate does the sphere

(a)

emit and

(b)

absorb thermal radiation?

(c)

What is the sphere's net change in energy in

3.50 \min

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Principles Of Physics International Student Version>Chapter 18 - Temperature, Heat, and the First Law of Thermodynamics>Problems>Q 30

If you were to walk briefly in space without a spacesuit while far from the Sun (as an astronaut does in the movie

2001,

A Space Odyssey), you would feel the cold of space - while you radiated energy, you would absorb almost none from your environment.
(a) At what rate would you lose energy?
(b) How much energy would you lose in

44 s

? Assume that your emissivity is

0.90,

and estimate other data needed in the calculations.

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Principles Of Physics International Student Version>Chapter 18 - Temperature, Heat, and the First Law of Thermodynamics>Problems>Q 31

Ice has formed on a shallow pond, and a steady-state has been reached, with the air above the ice at

- 5.0 ° C

and the bottom of the pond at

4.0 ° C

. If the total depth of ice and water is

2.0 m,

how thick is the ice? (Assume that the thermal conductivities of ice and water are

0.10

and

0.12 cal m^{- 1} {}^{°}C^{- 1} s^{- 1}

, respectively).

Calculate the minimum amount of energy, in joules, required to completely melt 85.0 g of silver initially at 15.0°C. [Given for silver, specific heat capacity s=236 J kg-1 k-1, and latent heat of fusion L=105000 J kg-1, melting point =1235 K]

Important Questions on Temperature, Heat, and the First Law of Thermodynamics

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Calculate the minimum amount of energy, in joules, required to completely melt $85.0 g$ of silver initially at $15.0 ° C$ . [Given for silver, specific heat capacity $s = 236 J {kg}^{- 1} k^{- 1}$ , and latent heat of fusion $L = 105000 J {kg}^{- 1}$ , melting point $= 1235 K$ ]