If an average person jogs, he produces $$14.5 \times10^3$$ cal/min. This is removed by the evaporation of sweat. The amount of sweat evaporated per minute (assuming $$1$$ kg requires $$580 \times10^3$$ cal for evaporation) is:
1. $$0.25$$ kg
2. $$0.50$$ kg
3. $$0.025$$ kg
4. $$0.20$$ kg

Subtopic:  First Law of Thermodynamics |
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Three copper blocks of masses  kg respectively are brought into thermal contact till they reach equilibrium. Before contact, they were at . Assuming there is no heat loss to the surroundings, the equilibrium temperature $$T$$ is: ($$s$$ is the specific heat of copper)

1. $T=\frac{{T}_{1}+{T}_{2}+{T}_{3}}{3}$

2. $T=\frac{{M}_{1}{T}_{1}+{M}_{2}{T}_{2}+{M}_{3}{T}_{3}}{{M}_{1}+{M}_{2}+{M}_{3}}$

3. $T=\frac{{M}_{1}{T}_{1}+{M}_{2}{T}_{2}+{M}_{3}{T}_{3}}{3\left({M}_{1}+{M}_{2}+{M}_{3}\right)}$

4. $T=\frac{{M}_{1}{T}_{1}s+{M}_{2}{T}_{2}s+{M}_{3}{T}_{3}s}{{M}_{1}+{M}_{2}+{M}_{3}}$

Subtopic:  First Law of Thermodynamics |
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An ideal gas undergoes an isothermal process from some initial state i to
the final state $f$.

(a) dU = 0

(b) dQ = 0

(c) dQ = dU

(d) dQ = dW

Choose the correct alternatives:

1. (a, b, c)

2. (a, d)

3. (b, c, d)

4. (a, c, d)

Subtopic:  First Law of Thermodynamics |
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Consider a cycle followed by an engine (figure).

1 to 2 is isothermal,

Such a process does not exist, because:

 a. heat is completely converted to mechanical energy in such a process, which is not possible. b. In this process, mechanical energy is completely converted to heat, which is not possible. c. curves representing two adiabatic processes don’t intersect. d. curves representing an adiabatic process and an isothermal process don't intersect.

Choose the correct alternatives:
1. (a, b)
2. (a, c)
3. (b, c)
4. (c, d)

Subtopic:  First Law of Thermodynamics | Second Law of Thermodynamics |
55%
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