1
JEE Main 2025 (Online) 23rd January Evening Shift
MCQ (Single Correct Answer)
+4
-1

The energy of a system is given as $\mathrm{E}(\mathrm{t})=\alpha^3 \mathrm{e}^{-b}$, where t is the time and $\beta=0.3 \mathrm{~s}^{-1}$. The errors in the measurement of $\alpha$ and $t$ are $1.2 \%$ and $1.6 \%$, respectively. At $t=5 \mathrm{~s}$, maximum percentage error in the energy is :

A
$6 \%$
B
$11.6 \%$
C
$4 \%$
D
$8.4 \%$
2
JEE Main 2025 (Online) 23rd January Evening Shift
MCQ (Single Correct Answer)
+4
-1

Match List - I with List - II

List - I List - II
(A) Permeability of free space (I) $\left[\mathrm{M} \mathrm{L}^2 \mathrm{~T}^{-2}\right]$
(B) Magnetic field (II) $\left[\mathrm{M} \mathrm{T}^{-2} \mathrm{~A}^{-1}\right]$
(C) Magnetic moment (III) $\left[\mathrm{M} \mathrm{L} \mathrm{T}^{-2} \mathrm{~A}^{-2}\right]$
(D) Torsional constant (IV) $\left[\mathrm{L}^2 \mathrm{~A}\right]$

Choose the correct answer from the options given below :

A
(A)-(III), (B)-(II), (C)-(IV), (D)-(I)
B
$(\mathrm{A})-(\mathrm{I}),(\mathrm{B})-(\mathrm{IV}),(\mathrm{C})-(\mathrm{II}),(\mathrm{D})-(\mathrm{III})$
C
$(\mathrm{A})-(\mathrm{II}),(\mathrm{B})-(\mathrm{I}),(\mathrm{C})-(\mathrm{III}),(\mathrm{D})-(\mathrm{IV})$
D
(A)-(IV), (B)-(III), (C)-(I), (D)-(II)
3
JEE Main 2025 (Online) 23rd January Evening Shift
MCQ (Single Correct Answer)
+4
-1

JEE Main 2025 (Online) 23rd January Evening Shift Physics - Heat and Thermodynamics Question 9 English

Using the given $P-V$ diagram, the work done by an ideal gas along the path $A B C D$ is :

A
$3 \mathrm{P}_0 \mathrm{~V}_0$
B
$-3 \mathrm{P}_0 \mathrm{~V}_0$
C
$-4 \mathrm{P}_0 \mathrm{~V}_0$
D
$4 \mathrm{P}_0 \mathrm{~V}_0$
4
JEE Main 2025 (Online) 23rd January Evening Shift
MCQ (Single Correct Answer)
+4
-1

A circular disk of radius R meter and mass M kg is rotating around the axis perpendicular to the disk. An external torque is applied to the disk such that $\theta(t)=5 t^2-8 t$, where $\theta(t)$ is the angular position of the rotating disc as a function of time $t$. How much power is delivered by the applied torque, when $t=2 \mathrm{~s}$ ?

A
$60 \mathrm{MR}^2$
B
$72 \mathrm{MR}^2$
C
$8 \mathrm{MR}^2$
D
$108 \mathrm{MR}^2$
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