Most Important Selected Qs for JEE AdvancedPhysicsRotational Motion
Paragraph: A smooth disc of mass M and radius R can rotate freely around a vertical axis supported by frictionless bearings. A constraining vertical surface of negligible mass, whose shape is a semicircular arc of radius r = R 2 , is fixed on the disc as shown in the figure. A small ball of mass m is placed on the stationary disc and is bowled at a speed v in such a way that it reaches the internal side of the constr
Options
- A2 mv MR M M +2 ~m
- B2 mv MR m M +2 ~m
- C2 mv MR 2 M M + m
- D2 mv MR M 2 M + m
Correct answer
A. 2 mv MR M M +2 ~m
Step-by-step solution
Let ball leaves with velocity u & disc rotates with clockwise direction Angular moment conservation about centre of disc L _ i = L _ f O = muR - ( MR ^2 2 ) = 2 mu MR (i) Energy conservation 1 2 m v^2= 1 2 m u^2+ 1 2 I ^2 (ii)u=v M M+2 m , =2 m v M R M M+2 m