Essay Question:
A blue and a green billiard ball, each with a mass of 0.15 kg collide directly. Before the collision, the blue ball had a speed of 3 m/s while the green ball had a speed of 2 m/s. After the collision, the blue ball stays in place while the green ball continues in motion.
Calculate the speed of the green ball after the collision and indicate the direction it is traveling after the collision.
You MUST use the conservation of momentum formula and follow the format given below.
Givens:
Unknown:
Equation:
Substitution:
Solve:
Given:
Mass of blue ball (mb) = 0.15 kg
Mass of green ball (mg) = 0.15 kg
Initial velocity of blue ball (vb) = 3 m/s
Initial velocity of green ball (vg) = 2 m/s
Final velocity of blue ball after collision (vb') = 0 m/s (stays in place)
Unknown:
Final velocity of green ball after collision (vg')
Equation:
Conservation of momentum:
(mb * vb) + (mg * vg) = (mb * vb') + (mg * vg')
Substitution:
(0.15 kg * 3 m/s) + (0.15 kg * 2 m/s) = (0.15 kg * 0 m/s) + (0.15 kg * vg')
Solve:
0.45 kg*m/s + 0.3 kg*m/s = 0 kg*m/s + 0.15 kg * vg'
0.75 kg*m/s = 0.15 kg * vg'
Dividing both sides of the equation by 0.15 kg:
5 m/s = vg'
Therefore, the speed of the green ball after the collision is 5 m/s and it continues in the same direction as its initial motion.