1
JEE Main 2021 (Online) 26th February Evening Shift
+4
-1
The length of metallic wire is l1 when tension in it is T1. It is l2 when the tension is T2. The original length of the wire will be :
A
$${{{T_1}{l_1} - {T_2}{l_2}} \over {{T_2} - {T_1}}}$$
B
$${{{l_1} + {l_2}} \over 2}$$
C
$${{{T_2}{l_1} + {T_1}{l_2}} \over {{T_1} + {T_2}}}$$
D
$${{{T_2}{l_1} - {T_1}{l_2}} \over {{T_2} - {T_1}}}$$
2
JEE Main 2021 (Online) 26th February Morning Shift
+4
-1
A large number of water drops, each of radius r, combine to have a drop of radius R. If the surface tension is T and mechanical equivalent of heat is J, the rise in heat energy per unit volume will be :
A
$${{2T} \over J}\left( {{1 \over r} - {1 \over R}} \right)$$
B
$${{3T} \over J}\left( {{1 \over r} - {1 \over R}} \right)$$
C
$${{3T} \over rJ}$$
D
$${{2T} \over rJ}$$
3
JEE Main 2021 (Online) 26th February Morning Shift
+4
-1
The normal density of a material is $$\rho$$ and its bulk modulus of elasticity is K. The magnitude of increase in density of material, when a pressure P is applied uniformly on all sides, will be :
A
$${{\rho K} \over P}$$
B
$${{PK} \over \rho }$$
C
$${{\rho P} \over K}$$
D
$${K \over {\rho P}}$$
4
JEE Main 2021 (Online) 24th February Morning Shift
+4
-1
If Y, K and $$\eta$$ are the values of Young's modulus, bulk modulus and modulus of rigidity of any material respectively. Choose the correct relation for these parameters.
A
$$Y = {{9K\eta } \over {3K - \eta }}N/{m^2}$$
B
$$Y = {{9K\eta } \over {2\eta + 3K}}N/{m^2}$$
C
$$\eta = {{3YK} \over {9K + Y}}N/{m^2}$$
D
$$K = {{Y\eta } \over {9\eta - 3Y}}N/{m^2}$$
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