1
JEE Main 2019 (Online) 12th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A vertical closed cylinder is separated into two parts by a frictionless piston of mass m and of negligible thickness. The piston is free to move along the length of the cylinder. The length of the cylinder above the piston is $$\ell $$1, and that below the piston is $$\ell $$2, such that $$\ell $$1 > $$\ell $$2. Each part of the cylinder contains n moles of an ideal gas at equal temperature T. If the piston is stationary, its mass, m, will be given by :
(R is universal gas constant and g is the acceleration due to gravity)
A
$${{nRT} \over g}\left[ {{{{\ell _1} - {\ell _2}} \over {{\ell _1}{\ell _2}}}} \right]$$
B
$${{RT} \over g}\left[ {{{2{\ell _1} + {\ell _2}} \over {{\ell _1}{\ell _2}}}} \right]$$
C
$${{nRT} \over g}\left[ {{1 \over {{\ell _2}}} + {1 \over {{\ell _1}}}} \right]$$
D
$${{RT} \over {ng}}\left[ {{{{\ell _1} - 3{\ell _2}} \over {{\ell _1}{\ell _2}}}} \right]$$
2
JEE Main 2019 (Online) 12th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
An ideal gas occupies a volume of 2m3 at a pressure of 3 $$ \times $$ 106 Pa. The energy of the gas is :
A
6 $$ \times $$ 104 J
B
9$$ \times $$ 106 J
C
3 $$ \times $$ 102 J
D
108 J
3
JEE Main 2019 (Online) 12th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A cylinder of radius R is surrounded by a cylindrical shell of inner radius R and outer radius 2R. The thermal conductivity of the material of the inner cylinder is K1 and the of the outer cylinder is K2. Assuming no loss of heat, the effective thermal conductivity of the system for heat flowing along the length of the cylinder is :
A
K1 + K2
B
$${{{K_1} + 3{K_2}} \over 4}$$
C
$${{{K_1} + {K_2}} \over 2}$$
D
$${{2{K_1} + 3{K_2}} \over 5}$$
4
JEE Main 2019 (Online) 12th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
For the given cyclic process CAB as shown for a gas, the work done is :

JEE Main 2019 (Online) 12th January Morning Slot Physics - Heat and Thermodynamics Question 286 English
A
1 J
B
10 J
C
5 J
D
30 J
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