1
JEE Main 2020 (Online) 5th September Evening Slot
+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
$${{{\alpha _1}{L_1} + {\alpha _2}{L_2}} \over {{L_1} + {L_2}}}$$
2
JEE Main 2020 (Online) 5th September Evening Slot
+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
$${1 \over {32}}$$
3
JEE Main 2020 (Online) 5th September Morning Slot
+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
4
JEE Main 2020 (Online) 5th September Morning Slot
+4
-1
Three different processes that can occur in an ideal monoatomic gas are shown in the P vs V diagram. The paths are labelled as A $$\to$$ B, A $$\to$$ C and A $$\to$$ D. The change in internal energies during these process are taken as EAB, EAC and EAD and the work done as WAB, WAC and WAD.
The correct relation between these parameters are :
A
B
EAB = EAC = EAD, WAB > 0, WAC = 0, WAD < 0
C