Question

At t = 0 the positions of two blocks are shown. Their is no external force acting on the system. Find the coordinates of center of mass of the system at t = 3 second :

A. (1, 0)
B. (3, 0)
C. (4, 5, 0)
D. (2, 25, 0)

Answer 1

Correct Answer - D

Initial velocity of COM
`=(m_(1)vecv_(1)+m_(2)vecv_(2))/(m_(1)+m_(2))=(4xx2+4(-2))/(8)=0m//s`
`because` No external force acts on the system & initial velocity of COM is zero. Hence COM remain at rest.
Initial `"Oss"^(n)` of COM
`x_(cm)=(0xx4+4.5xx4)/(8)=2.25`