Question

A 100 kg mass, initially at rest, is blown apart into a 60 kg piece and a 40 kg piece. After the blast, the two masses are moving apart with a relative velocity of 60 m/s. The speed of the 60 kg mass is

Answer 1

Step-by-step explanation:

According to law of conservation of momentum

(m1+m2)v = m1u1+m2u2

Let m1 and m2 be the masses

u1 and u2 be their respective velocities

v is the velocity of combined objects

Given

m1 =60kg

m2 = 40kg

v =0 m/s

u2 - u1 = 60 ............ 1

0 = 60u1 + 40u2 = 0 .......... 2

From 1: u2 = 60+u1

Substitute into 2:

60u1 + 40(60+u1) = 0

60u1 +2400 +40u1 = 0

100u1 = -2400

u1 = -2400/100

u1 = -24m/s

Hence the speed of the 60 kg mass is 24m/s (in the negative direction)