JEE Advanced2008PhysicsCenter of Mass, Momentum and CollisionActual
Paragraph: A small block of mass M moves on a frictionless surface of an inclined plane, as shown in figure. The angle of the incline suddenly changes from 60^ to 30^ at point B . The block is initially at rest at A . Assume that collisions between the block and the incline are totally inelastic (g=10 ~m / s ^2 ) Question: The speed of the block at point C , immediately before it leaves the second incline is
Options
- A120 ~m / s
- B105 ~m / s
- C90 ~m / s
- D75 ~m / s
Correct answer
B. 105 ~m / s
Step-by-step solution
Height fallen by the block from B to C . h₂=3 3 30^ =3 ~m Let v₃ be the speed of block, at point C , just before it leaves the second incline, then aligned v₃ & = v₂^2+2 g h₂ & = 45+2 10 3 & = 105 ~ms ⁻¹ aligned correct option is (b).