JEE Main 2020 (Online) 2nd September Morning Slot | Rotational Motion Question 87 | Physics

JEE Main 2020 (Online) 2nd September Morning Slot

MCQ (Single Correct Answer)

-1

A bead of mass m stays at point P(a, b) on a wire bent in the shape of a parabola y = 4Cx² and rotating with angular speed $$\omega $$ (see figure). The value of $$\omega $$ is (neglect friction) : JEE Main 2020 (Online) 2nd September Morning Slot Physics - Rotational Motion Question 88 English

JEE Main 2020 (Online) 2nd September Morning Slot Physics - Rotational Motion Question 88 English

$$2\sqrt {2gC} $$

$$2\sqrt {gC} $$

$$\sqrt {{{2gC} \over {ab}}} $$

$$\sqrt {{{2g} \over C}} $$

JEE Main 2020 (Online) 9th January Evening Slot

MCQ (Single Correct Answer)

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A spring mass system (mass m, spring constant k and natural length $$l$$) rest in equilibrium on a horizontal disc. The free end of the spring is fixed at the centre of the disc. If the disc together with spring mass system, rotates about it's axis with an angular velocity $$\omega $$, (k $$ \gg m{\omega ^2}$$) the relative change in the length of the spring is best given by the option :

$${{m{\omega ^2}} \over {3k}}$$

$${{m{\omega ^2}} \over k}$$

$${{2m{\omega ^2}} \over k}$$

$$\sqrt {{2 \over 3}} \left( {{{m{\omega ^2}} \over k}} \right)$$

JEE Main 2020 (Online) 9th January Evening Slot

MCQ (Single Correct Answer)

-1

A rod of length L has non-uniform linear mass
density given by $$\rho $$(x) = $$a + b{\left( {{x \over L}} \right)^2}$$ , where a
and b are constants and 0 $$ \le $$ x $$ \le $$ L. The value
of x for the centre of mass of the rod is at :

$${3 \over 2}\left( {{{a + b} \over {2a + b}}} \right)L$$

$${4 \over 3}\left( {{{a + b} \over {2a + 3b}}} \right)L$$

$${3 \over 4}\left( {{{2a + b} \over {3a + b}}} \right)L$$

$${3 \over 2}\left( {{{2a + b} \over {3a + b}}} \right)L$$

JEE Main 2020 (Online) 9th January Evening Slot

MCQ (Single Correct Answer)

-1

A uniformly thick wheel with moment of inertia I and radius R is free to rotate about its centre of mass (see fig). A massless string is wrapped over its rim and two blocks of masses m₁ and m₂ (m₁ $$ > $$ m₂) are attached to the ends of the string. The system is released from rest. The angular speed of the wheel when m₁ descents by a distance h is : JEE Main 2020 (Online) 9th January Evening Slot Physics - Rotational Motion Question 89 English