Three bodies having masses 5 kg, 4 kg and 2 kg are moving at the speeds of 5 ms-1, 4 ms-1 and 2 ms-1, respectively along X-axis. The magnitude of velocity of centre of mass is [AllMS 2018]

Velocity of centre of mass,          νCM=m1v1+m2v2+m33m1+m2+m3Given, m1=5 kg, v1=5ms-1,           m2=4 kg, v2=4 ms-1, m3 = 2kg and v3 = 2 ms-1Substituting all these values in above equation, we get           νCM=5×5+4×4+2×25+4+2=25+16+411∴      vCM=4511=4.09≈4 ms-1