1
JEE Main 2020 (Online) 8th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Consider a uniform rod of mass M = 4m and length $$\ell $$ pivoted about its centre. A mass m moving with velocity v making angle $$\theta = {\pi \over 4}$$ to the rod's long axis collides with one end of the rod and sticks to it. The angular speed of the rod-mass system just after the collision is :
A
$${{3\sqrt 2 } \over 7}{v \over \ell }$$
B
$${3 \over 7}{v \over \ell }$$
C
$${3 \over {7\sqrt 2 }}{v \over \ell }$$
D
$${4 \over 7}{v \over \ell }$$
2
JEE Main 2020 (Online) 8th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
The coordinates of centre of mass of a uniform flag shaped lamina (thin flat plate) of mass 4kg. (The coordinates of the same are shown in figure) are : JEE Main 2020 (Online) 8th January Morning Slot Physics - Rotational Motion Question 110 English
A
(0.75m, 1.75m)
B
(1m, 1.75m)
C
(0.75m, 0.75m)
D
(1.25m, 1.50m)
3
JEE Main 2020 (Online) 8th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
A particle of mass m is fixed to one end of a light spring having force constant k and unstretched length $$\ell $$. The other end is fixed. The system is given an angular speed $$\omega $$ about the fixed end of the spring such that it rotates in a circle in gravity free space. Then the stretch in the spring is :
A
$${{m\ell {\omega ^2}} \over {k - m{\omega ^2}}}$$
B
$${{m\ell {\omega ^2}} \over {k - m{\omega}}}$$
C
$${{m\ell {\omega ^2}} \over {k + m{\omega ^2}}}$$
D
$${{m\ell {\omega ^2}} \over {k + m{\omega}}}$$
4
JEE Main 2020 (Online) 7th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Mass per unit area of a circular disc of radius $$a$$ depends on the distance r from its centre as $$\sigma \left( r \right)$$ = A + Br . The moment of inertia of the disc about the axis, perpendicular to the plane and assing through its centre is:
A
$$2\pi {a^4}\left( {{A \over 4} + {{aB} \over 5}} \right)$$
B
$$\pi {a^4}\left( {{A \over 4} + {{aB} \over 5}} \right)$$
C
$$2\pi {a^4}\left( {{{aA} \over 4} + {B \over 5}} \right)$$
D
$$2\pi {a^4}\left( {{A \over 4} + {B \over 5}} \right)$$
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