Answer:
Explanation:
given,
moles of air compressed, n = 1.70 mol
initial temperature, T₁ = 390 K
Power supply by the compressor, P = 7.5 kW
Heat removed = 1.3 kW
Angular frequency of the compressor, f = 110 rpm = 110/60 = 1.833 rps.
Time of compression = time of the hay revolution
=
=
=
=0.273 s
Using first law of thermodynamics
U = Q - W
now,
Power supplied 
= 7.5 kW
heat removed 
= 1.3 kW
now,
we know,
C_v for air = 5 cal/° mol
= 5 x 4.186 J/mol°C = 20.93 J/mol°C
now,
the temperature change per compression stroke is equal to 47.57°C.
When sugar is first heated, it begins to melt. As it melts its color starts to change from white to golden brown, and then to dark brown (if you continue heating it). If you apply heat for even longer, it becomes black and gives off unpleasant fumes.
Answer:
B
Explanation:
This happens because adding salt to the water decreases Its density. When the density of the water matches that of the egg, the egg becomes neutrally buoyant and floats.
The weight of the egg becomes equal to the upward buoyant force by the water on to the egg and hence, the egg floats.
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Rock is completely immersed in hot water. By the second law of thermodynamics, thermal energy or heat is transferred from substance with higher temperature to substance with lower temperature until they come to thermal equilibrium i.e. both at same temperature.
It is given here that rock is at 20°C which is at lower temperature than water at 80°C. ∴Heat or thermal energy flows from water to rock. So, right choice is-
A. The water gives the rock thermal energy and gets no thermal energy in return.
