JEE Main 2019 (Online) 12th April Morning Slot | Center of Mass and Collision Question 68 | Physics

JEE Main 2019 (Online) 12th April Morning Slot

MCQ (Single Correct Answer)

-1

A man (mass = 50 kg) and his son (mass = 20 kg) are standing on a frictionless surface facing each other. The man pushes his son so that he starts moving at a speed of 0.70 ms^–1 with respect to the man. The speed of the man with respect to the surface is :

0.28 ms^–1

0.47 ms^–1

0.20 ms^–1

0.14 ms^–1

JEE Main 2019 (Online) 10th April Evening Slot

MCQ (Single Correct Answer)

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A solid sphere of mass M and radius R is divided into two unequal parts. The first part has a mass of $${{7M} \over 8}$$ and is converted into a uniform disc of radius 2R. The second part is converted into a uniform solid sphere. Let I₁ be the moment of inertia of the disc about its axis and I₂ be the moment of inertia of the new sphere about its axis. The ratio I₁/I₂ is given by :

140

185

285

JEE Main 2019 (Online) 10th April Evening Slot

MCQ (Single Correct Answer)

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The time dependence of the position of a particle of mass m = 2 is given by $$\overrightarrow r \left( t \right) = 2t\widehat i - 3{t^2}\widehat j$$ . Its angular momentum, with respect to the origin, at time t = 2 is

36 $$\widehat k$$

- 48 $$\widehat k$$

$$ - 34\left( {\widehat k - \widehat i} \right)$$

$$48\left( {\widehat i + \widehat j} \right)$$

JEE Main 2019 (Online) 10th April Morning Slot

MCQ (Single Correct Answer)

-1

A thin disc of mass M and radius R has mass per unit area $$\sigma $$(r) = kr² where r is the distance from its centre. Its moment of inertia about an axis going through its centre of mass and perpendicular to its plane is :

$${{M{R^2}} \over 3}$$

$${{M{R^2}} \over 6}$$

$${{2M{R^2}} \over 3}$$

$${{M{R^2}} \over 2}$$

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