A body of mass M at rest explodes into three pieces, two of which of mass M/4 each are thrown off in perpendicular directions with velocities of 3m/s and 4m/s respectively . Find the velocity of third piece.
Open in App
Solution
Initial mass = M initial velocity = 0
After explosion, m1 = M/4 v1 = 3m/s i (i means along x-direction) m2 = M/4 v2 = 4m/s j (j means along y-direction) m3 = M-(M/4 + M/4) = M/2 v3 = V
As there is no external force, momentum before explosion = momentum after explosion ⇒M(0) = m1v1 + m2v2 + m3v3 ⇒ 0 = M/4 (3)i + M/4 (4)j + M/2(V) ⇒ 0 = M [ (3/4)i + 1j + V/2 ] ⇒ 0 = (3/4)i + 1j + V/2 ⇒ V/2 = -[(3/4)i + 1j] ⇒ V = 2×-[(3/4)i + 1j] ⇒ V = -[ (3/2)i +(2)j ] ⇒ V = -(3/2)i -2j |V| = √[(3/2)² + 2²] = 2.5m/s