ROTATIONAL MOTION ASSIGNMENT

Assignment of rotational motion (class 11)

Q.1 Why is the speed of whirl wind in a tornado alarmingly high?
(Use L = Iw)

Q.2 If Earth was to shrink suddenly to half its radius, what will happen to the length of the day?
(Use I=2/5Mr^2 and L=Iw)
Ans. Decreases

Q.3 When there is no external torque on the rotating body which of the following questions can change:-
1) Angular acc
2) Angular momentum
3) Angular Speed

Q.4 Equal torques are applied on a cylinder and a hollow sphere. Both have the same mass and radius. The cylinder rotates about its axis and the sphere about one of its diameters . which will acquire greater speed.
Torque=I*angular acc. Angular acc= torqe/I
Q.5 Asolid sphere is made to roll down from the same ht. on two inclined planes having having theta 2>theta 1. in which case will it take less time to reach the bottom?
Ans. In case of theta 2.

Q.6 The moment of inertia of 2 rotating bodies A&B are Ia & Ib (Ia>Ib)
And their angular momenta are equal. Which has greater k.i.?
Ans. B

Q.7 If the polar ice caps melts, how will it affect the duration of the day?
L=Iw=const.
Ans. L.w=2pie/T therefore, length of the day will increase.