Question

A 6 kg bomb at rest explodes into three equal
pieces P, Q and R. If P flies with speed 30 m/s
and Q with speed 40 m/s making an angle 90° with
the direction of P. The angle between the direction
of motion of P and R is about
(1) 143°
(2) 127°
(4) 150°
(3) 120°

Answer 1

There is no external force in the given system.

Here》 Momentum is conserved:《

Momentum of particleP=30×2=60

Momentum of particleQ=40×2=80

Resultant of Momentum of particle P and Q will be equal to Momentum of particle R

So, ∣R∣=|P+Q|

=>|R| =(60)2+(80)2+2PQcos90​

=>∣R∣=100

=>∣mv∣=100

=>∣v∣=50m/s

ALSO,

∣Q∣2=∣P∣2+∣R∣2 +2PRcosθ 1600=900+2500+2×1500×cosθ then cosθ=−(0.6) θ=127°