1
JEE Main 2014 (Offline)
+4
-1
Three rods of Copper, Brass and Steel are welded together to form a $$Y$$ shaped structure. Area of cross - section of each rod $$= 4c{m^2}.$$ End of copper rod is maintained at $${100^ \circ }C$$ where as ends of brass and steel are kept at $${0^ \circ }C$$. Lengths of the copper, brass and steel rods are $$46,$$ $$13$$ and $$12$$ $$cms$$ respectively. The rods are thermally insulated from surroundings excepts at ends. Thermal conductivities of copper, brass and steel are $$0.92, 0.26$$ and $$0.12$$ $$CGS$$ units respectively. Rate of heat flow through copper rod is:
A
$$1.2$$ $$cal/s$$
B
$$2.4$$ $$cal/s$$
C
$$4.8$$ $$cal/s$$
D
$$6.0$$ $$cal/s$$
2
JEE Main 2014 (Offline)
+4
-1
One mole of a diatomic ideal gas undergoes a cyclic process $$ABC$$ as shown in figure. The process $$BC$$ is adiabatic. The temperatures at $$A, B$$ and $$C$$ are $$400$$ $$K$$, $$800$$ $$K$$ and $$600$$ $$K$$ respectively. Choose the correct statement :
A
The change in internal energy in whole cyclic process is $$250$$ $$R.$$
B
The change in internal energy in the process $$CA$$ is $$700$$ $$R$$.
C
The change in internal energy in the process $$AB$$ is - $$350$$ $$R.$$
D
The change in internal energy in the process $$BC$$ is - $$500$$ $$R.$$
3
JEE Main 2013 (Offline)
+4
-1
Assume that a drop of liquid evaporates by decreases in its surface energy, so that its temperature remains unchanged. What should be the minimum radius of the drop for this to be possible ? The surface tension is $$T,$$ density of liquid is $$\rho$$ and $$L$$ is its latent heat of vaporization.
A
$$\rho L/T$$
B
$$\sqrt {T/\rho L}$$
C
$$T/\rho L$$
D
$$2T/\rho L$$
4
JEE Main 2013 (Offline)
+4
-1

The above $$p$$-$$v$$ diagram represents the thermodynamic cycle of an engine, operating with an ideal monatomic gas. The amount of heat, extracted from the source in a single cycle is

A
$${p_0}{v_0}$$
B
$$\left( {{{13} \over 2}} \right){p_0}{v_0}$$
C
$$\left( {{{11} \over 2}} \right){p_0}{v_0}$$
D
$$4{p_0}{v_0}$$
EXAM MAP
Medical
NEET