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?
- 1.5 ms-1
- 1.4 ms-1
- 2.1 ms-1
-
1.7 ms-1
The correct answer is: D
Explanation
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
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