A sandbag is motionless in outer space. A second sandbag with 3 times the mass moving at 12 m/s collides with it. They stick together and move at a speed of

Question

Quizplus · Accepted Answer

The conservation of momentum principle is used to solve this problem. The total momentum before the collision must equal the total momentum after the collision. Let's denote the mass of the first sandbag as $m$ and the mass of the second sandbag as $3m$. The initial momentum is $3m \times 12\ m/s$, since the first sandbag is motionless. After the collision, the combined mass is $4m$ and they move together with a speed $v$. Setting the initial momentum equal to the final momentum, we get $3m \times 12 = 4m \times v$. Solving for $v$ gives $v = 9\ m/s$, which is not listed among the options, making E (none of these) the correct choice.

A Sandbag Is Motionless in Outer Space