Two bodies of masses `1 kg and 2 kg` are moving in two perpendicular direction with velocities `1 m//s and 2 m//s` as shown in figure. The velocity of the centre of mass (in magnitide) of the system will be :

Options

A. `3 m//s`
B. `1.67 m//s`
C. `1.5 m//s`
D. `1.37 m//s`

Answer

D

Explanation

(d) `vec v_(cm) = (1 xx hat i + 2 xx 2 hat j)/(1 + 2) = (hat i + 4 hat j)/(3)`
`|vec v_(cm)| = (1)/(3) sqrt(1^2 + 4^2) = (sqrt(17))/(3) = 1.37 m//s`.