Question

The block of mass $m=12kg$ is at rest just before the collision.
If the collision between the blocks is inelastic and they stick together after the collision, with what speed would they move?

• A. $2.0m/s$
• B. $2.7m/s$
• C. $3.2m/s$
• D. $4.0m/s$
• E. $4.6m/s$

Answer 1

The correct option is A $2.0m/s$

Let $v$ be the speed of them after stuck together.

Using conservation of momentum,

momentum after collision $=$ momentum before collision

or $(4+12)v=4\left(8\right)+m\left(0\right)$

or $v=2m/s$