A body of mass 12kg traveling at 4.2ms-1 collides with a second body of mass 18kg at rest. Calculate their common velocity if the two bodies coalesce after collision
-
A.
1.5 ms-1 -
B.
1.4 ms-1 -
C.
2.1 ms-1 -
D.
1.7 ms-1
Correct Answer: Option D
Explanation
Sum of momentum before collision
M1 U1 + M2M2
12 x 4.2 + 18 x 0
12 x 4.2
= 50.4
Sum of momentum after collision
(m1 + m2)v
= (12 + 18)v
= 30v
V = 50.4/30
= 1.7ms-1