A 3.0-kg and a 2.0-kg cart approach each other on a horizontal air track. They collide and stick together. After the collision their total kinetic energy is 40 J. The speed of their center of mass is:
A) zero
B) 2.8 m/s
C) 4.0 m/s
D) 5.2 m/s
E) 6.3 m/s

Question

Quizplus · Accepted Answer

The total kinetic energy after the collision is given as 40 J. The combined mass of the carts is 5.0 kg (3.0 kg + 2.0 kg). Using the kinetic energy formula $ KE = \frac{1}{2}mv^2 $, we can solve for the speed of the center of mass: $ 40 = \frac{1}{2} \times 5 \times v^2 $. Solving for $ v $, we get $ v = 4.0 $ m/s.

A 30-Kg and a 2