Question

A 3 kg block moving at velocity 10 m/s when it collides with and sticks to another 2 kg block initially at rest, as in the fig below. How far up from ground do both blocks travel on the incline plane?

Answer 1

let velocity of combined mass after the collision is v. By conservation of linear momentum

(3 kg ) (10 m/s) = (3 kg + 2 kg) v

v = (3/5) (10 m/s)

= 6 m/s

Let maximum height reached by combined mass is h . At highest point velocity becomes zero. By conservation of mechanical energy,

mgh = (1/2) m v²

h = v²/(2 g) = 6²/(2 x 9.8) = 1.84 m