JEE Main 2021 (Online) 17th March Morning Shift | Rotational Motion Question 51 | Physics

JEE Main 2021 (Online) 17th March Morning Shift

MCQ (Single Correct Answer)

-1

A mass M hangs on a massless rod of length l which rotates at a constant angular frequency. The mass M moves with steady speed in a circular path of constant radius. Assume that the system is in steady circular motion with constant angular velocity $$\omega$$. The angular momentum of M about point A is L_A which lies in the positive z direction and the angular momentum of M about point B is L_B. The correct statement for this system is :

JEE Main 2021 (Online) 17th March Morning Shift Physics - Rotational Motion Question 53 English

JEE Main 2021 (Online) 17th March Morning Shift Physics - Rotational Motion Question 53 English

L_A is constant, both in magnitude and direction

L_B is constant in direction with varying magnitude

L_B is constant, both in magnitude and direction

L_A and L_B are both constant in magnitude and direction

JEE Main 2021 (Online) 16th March Morning Shift

MCQ (Single Correct Answer)

-1

A block of 200 g mass moves with a uniform speed in a horizontal circular groove, with vertical side walls of radius 20 cm. If the block takes 40 s to complete one round, the normal force by the side walls of the groove is :

9.859 $$\times$$ 10^$$-$$2 N

0.0314 N

9.859 $$\times$$ 10^$$-$$4 N

6.28 $$\times$$ 10^$$-$$3 N

JEE Main 2021 (Online) 16th March Morning Shift

MCQ (Single Correct Answer)

-1

The maximum and minimum distances of a comet from the Sun are 1.6 $$\times$$ 10¹² m and 8.0 $$\times$$ 10¹⁰ m respectively. If the speed of the comet at the nearest point is 6 $$\times$$ 10⁴ ms^$$-$$1, the speed at the farthest point is :

3.0 $$\times$$ 10³ m/s

6.0 $$\times$$ 10³ m/s

1.5 $$\times$$ 10³ m/s

4.5 $$\times$$ 10³ m/s

JEE Main 2021 (Online) 26th February Evening Shift

MCQ (Single Correct Answer)

-1

A cord is wound round the circumference of wheel of radius r. The axis of the wheel is horizontal and the moment of inertia about it is I. A weight mg is attached to the cord at the end. The weight falls from rest. After falling through a distance 'h', the square of angular velocity of wheel will be :

$${{2mgh} \over {I + 2m{r^2}}}$$

$${{2mgh} \over {I + m{r^2}}}$$

2gh

$${{2gh} \over {I + m{r^2}}}$$

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