Two skaters A and B are moving in opposite directions such as they collide head - on and immediately become entangled. Skater A has a mass of 40 kg and is moving with a velocity 4 m/s eastwards while the other skater B has a mass of 60 kg and is moving with a velocity 3 m/ westwards. Assume that hte frictional force acting between the skaters and the ground is negligible

The magnitude of total momentum of the two skaters before collision is

Options

A. `40 kg m s^(-1)`
B. `20 kg m s^(-1)`
C. `10 kg m s^(-1)`
D. `60 kg m s^(-1)`

Answer

B

Explanation

`m_(1) = 40 kg , u_(1) = 4 m//s and m_(2) = 60 kg, u_(2) = 3 m//s `
The total momentum of the two skaters before collision ,
`m_(1) u_(1) - m_(2) u_(2) = 40 xx 4 - 60 xx 3 = - 20 kg m//s`