A 3.0 kg puck moving at 2.0 m/s strikes a stationary 2.0 kg puck. After the collision, the 3.0 kg puck has a velocity of 0.40 m/s. Use conservation of momentum to find the velocity of the 2.0 kg puck after the collision.

2.4 m/s

Explanation:

Applying,

The law of conservation of momentum

Total momentum before collision = Total momentum after collision

mu+m'u' = mv+m'v' Equation 1

Where m = mass of the moving puck, m' = mass of the stationary puck, u = initial velocity of the moving puck, u' = initial velocity of the stationary puck, v = final velocity of the moving puck, v' = final velocity of the stationary puck.

make v' the subject of the equation

v' = (mu+m'u'-mv)/m' Equation 2

From the question,

Given; m = 3 kg, m' = 2 kg, u = 2 m/s, u' = 0 m/s (stationary), v = 0.4 m/s

Substitute these values into equation 2

v' = [(3×2)+(2×0)-(3×0.4)]/2

v' = (6-1.2)/2

v' = 4.8/2

v' = 2.4 m/s

the average speed is 24.57 km/hr

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