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
Verified Correct Answer: D.
Physical Principles & Numerical Solution
The sum of momentum before collision
M\(_1\) U\(_1\) + M\(_2\)U\(_2\)
12 x 4.2 + 18 x 0
12 x 4.2
= 50.4
The sum of momentum after collision
(m\(_1\) + m\(_2\))v
= (12 + 18)v
= 30v
V = 50.4/30
= 1.7ms-1
Source: WAEC / JAMB / NECO Classroom Archive (Record #14498)