1
JEE Main 2021 (Online) 25th July Evening Shift
Numerical
+4
-1
A solid disc of radius 20 cm and mass 10 kg is rotating with an angular velocity of 600 rpm, about an axis normal to its circular plane and passing through its centre of mass. The retarding torque required to bring the disc at rest in 10 s is ____________ $$\pi$$ $$\times$$ 10$$-$$1 Nm.
2
JEE Main 2021 (Online) 25th July Morning Shift
Numerical
+4
-1
A particle of mass 'm' is moving in time 't' on a trajectory given by

$$\overrightarrow r = 10\alpha {t^2}\widehat i + 5\beta (t - 5)\widehat j$$

Where $$\alpha$$ and $$\beta$$ are dimensional constants.

The angular momentum of the particle becomes the same as it was for t = 0 at time t = ____________ seconds.
3
JEE Main 2021 (Online) 22th July Evening Shift
Numerical
+4
-1
The centre of a wheel rolling on a plane surface moves with a speed v0. A particle on the rim of the wheel at the same level as the centre will be moving at a speed $$\sqrt x {v_0}$$. Then the value of x is _____________.
4
JEE Main 2021 (Online) 20th July Evening Shift
Numerical
+4
-1
Two bodies, a ring and a solid cylinder of same material are rolling down without slipping an inclined plane. The radii of the bodies are same. The ratio of velocity of the centre of mass at the bottom of the inclined plane of the ring to that of the cylinder is $${{\sqrt x } \over 2}$$. Then, the value of x is _____________.