1
JEE Main 2020 (Online) 6th September Morning Slot
MCQ (Single Correct Answer)
+4
-1
Molecules of an ideal gas are known to have three translational degrees of freedom and two rotational degrees of freedom.The gas is maintained at a temperature of T. The total internal energy, U of a mole of this gas, and the value of
$$\gamma \left( { = {{{C_p}} \over {{C_v}}}} \right)$$ are given, respectively by:
A
U = $${5 \over 2}RT$$ and $$\gamma = {7 \over 5}$$
B
U = 5RT and $$\gamma = {6 \over 5}$$
C
U = 5RT and $$\gamma = {7 \over 5}$$
D
U = $${5 \over 2}RT$$ and $$\gamma = {6 \over 5}$$
2
JEE Main 2020 (Online) 5th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
Two different wires having lengths L1 and L2, and respective temperature coefficient of linear expansion $$\alpha $$1 and $$\alpha $$2, are joined end-to-end. Then the effective temperature coefficient of linear expansion is :
A
$$2\sqrt {{\alpha _1}{\alpha _2}} $$
B
$$4{{{\alpha _1}{\alpha _2}} \over {{\alpha _1} + {\alpha _2}}}{{{L_2}{L_1}} \over {{{\left( {{L_2} + {L_1}} \right)}^2}}}$$
C
$${{{\alpha _1} + {\alpha _2}} \over 2}$$
D
$${{{\alpha _1}{L_1} + {\alpha _2}{L_2}} \over {{L_1} + {L_2}}}$$
3
JEE Main 2020 (Online) 5th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
In an adiabatic process, the density of a diatomic gas becomes 32 times its initial value. The final pressure of the gas is found to be n times the initial pressure. The value of n is :
A
128
B
32
C
326
D
$${1 \over {32}}$$
4
JEE Main 2020 (Online) 5th September Morning Slot
MCQ (Single Correct Answer)
+4
-1
A bullet of mass 5 g, travelling with a speed of 210 m/s, strikes a fixed wooden target. One half of its kinetic energy is converted into heat in the bullet while the other half is converted into heat in the wood. The rise of temperature of the bullet if the specific heat of its material is 0.030 cal/(g – oC) (1 cal = 4.2 × 107 ergs) close to :
A
87.5 oC
B
83.3 oC
C
38.4 oC
D
119.2 oC
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