An object of mass m is projected vertically upwards with a speed of v0. At the same moment another object of mass M, which is initially above the projected one, is dropped from a height of h. The two point like objects collide completely inelastically, and they stick to each other. Find kinetic energy (in J) of combined mass just before it hits the ground.
(Given : m = 1 kg, v0 = 20 m/s, M = 3 kg, h = 20 m, g = 10 m/s2)
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Using relative velocity time of slight before collision will be
By COM at the time of collision
3 × 10 – 1 × 10 = 4 × v
2 × 10 = 4 × v
5 = v
v = 5 ms–1
For 1-D motion
v2 = u2 + 2 as
= 52 + 2 × 10 × 15
= 25 + 300 = 325
K = 650 J