Given below are two statements:
Assertion (A): | The speed of whirlwind in a tornado is alarmingly high. |
Reason (R): | If no external torque acts on a body, its angular velocity remains conserved. |
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | Both (A) and (R) are false. |
A cylinder of mass 'M' is suspended by two strings wrapped around it as shown. The acceleration 'a' and the tension T when the cylinder falls and the string unwinds itself are, respectively,
1.
2.
3.
4.
An automobile engine develops 100 kW when rotating at a speed of 1800 rev/min. What torque does it deliver ?
1. 350 N-m
2. 440 N-m
3. 531 N-m
4. 628 N-m
A bob of mass m attached to an inextensible string of length l is suspended from vertical support. The bob rotates in a horizontal circle with an angular speed about the vertical. About the point of suspension.
1. | Angular momentum is conserved |
2. | Angular momentum changes in magnitude but not in the direction |
3. | Angular momentum changes in direction but not in magnitude |
4. | Angular momentum changes both in direction and magnitude |
A wheel is at rest. Its angular velocity increases uniformly and becomes 80 rad/s after 5 s. The total angular displacement is
1. 800 rad
2. 400 rad
3. 200 rad
4. 100 rad
A constant torque acting on a uniform circular wheel changes its angular momentum from to in 4s. The magnitude of this torque is
1.
2.
3.
4.
A body rolls down an inclined plane without slipping. The fraction of total energy associated with its rotation will be
Where k is radius of gyration of the body about an axis passing through centre of mass and R is the radius of the body.
A solid cylinder rolls down an inclined plane that has friction sufficient to prevent sliding. The ratio of rotational energy to total kinetic energy is
1.
2.
3.
4.
A swimmer while jumping into water from a height easily forms a loop in the air, if
1. | He pulls his arms and legs in |
2. | He spreads his arms and legs |
3. | He keeps himself straight |
4. | None of the above |