A 550-g mass traveling at 8.0 m/s undergoes a head-on elastic collision with a 250-g mass traveling toward it also at 8.0 m/s. What is the speed of the 250-g mass after the collision?
A) 15 m/s
B) 8.0 m/s
C) 4.0 m/s
D) 14 m/s
E) 0 m/s

Question

Quizplus · Accepted Answer

Explanation:Momentum is conserved in the collision, so the total momentum before the collision is equal to the total momentum after the collision. The 550-g mass has a momentum of 550 g * 8.0 m/s = 4400 g m/s, and the 250-g mass has a momentum of 250 g * 8.0 m/s = 2000 g m/s. The total momentum before the collision is therefore 4400 g m/s + 2000 g m/s = 6400 g m/s. After the collision, the 550-g mass has a momentum of 550 g * v = 550 v g m/s, and the 250-g mass has a momentum of 250 g * v = 250 v g m/s. The total momentum after the collision is therefore 550 v g m/s + 250 v g m/s = 800 v g m/s. Since momentum is conserved, we have 6400 g m/s = 800 v g m/s, so v = 8.0 m/s. The speed of the 250-g mass after the collision is therefore 8.0 m/s.

A 550-G Mass Traveling at 8