A particle P is projected from a point on the surface of smooth inclined plane (see figure). Simultaneously another particle Q is released on the smooth inclined plane from the same position. P and Q collide after`t=4`. The speed of projection of P is

Options

A. Trajectory of particle `P` in the frame of `Q` is parabola during the flight of particle `P`
B. Speed of projection of `P` is `20m//s`
C. Relative velocity of Particle `P` in the frame of `Q` changes linearly with time during the flight of `P`.
D. Acceleration of particle `P` in the frame of `Q` is zero during the flight of `P`

Answer

C

Explanation

Acceleration of particle `P` and `Q` along the incline is same. Acceleration of particle `P` perpendicular to the incline plane is `10 cos 60^(@)=m//s^(2)`
So, `v_(P)-5(2)=0`
`:. v_(P)=10m//s`