Question

Two spheres of mass 4 kg and 8kg are moving with velocity 2 and 3ms away from each other along the same line find the velocity of centre of mass

Answer 1

M1=2kg

M2=1kg

initial velocity of M1=3m/s

initial velocity of M2=4m/s

applying law of conservation of momentum

M1V1+M2V2=M1U1+M2U2

since final velocity is same

V(M1+M2)=M1U1+M2U2

V(2+1)=2*3+1*(-4)(negative because in the opposite direction)

V*3=6+(-4)

V*3+6-4

V*3=2

V=2/3

hence the answer is 2/3 m/s.

Answer 2

Answer:

4/3 m/s in direction of the heavier mass

Explanation:

velocity of centre of mass

$v = \frac{m1v1 + m2v2}{m1 + m2}$

putting

m1= 8

m2= 4

v1 = 3

v2 = -2

u can solve and get 16/12 ie 4/3 as answer