Answer:
3.38 m/s
Explanation:
Mass of child = m₁ = 25
Initial speed of child = u₁ = 5 m/s
Initial speed of cart = u₂ = 0 m/s
Mass of cart = m₂ = 12 kg
Velocity of cart with child on top = v
This is a case of perfectly inelastic collision

Velocity of cart with child on top is 3.38 m/s
The initial velocity of the ball is 55.125 m/s.
<h3>Initial velocity of the ball</h3>
The initial velocity of the ball is calculated as follows;
During upward motion
h = vi - ¹/₂gt²
h = vi - 0.5(9.8)(3²)
h = vi - 44.1 ----------------- (1)
During downward motion
h = vi + ¹/₂gt²
h = 0 + 0.5(9.8)(1.5)²
h = 11.025 ----------- (2)
solve (1) and (2) together, to determine the initial velocity of the ball
11.025 = vi - 44.1
vi = 11.025 + 44.1
vi = 55.125 m/s
Thus, the initial velocity of the ball is 55.125 m/s.
Learn more about initial velocity here: brainly.com/question/19365526
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I think that in order for work to be done, the object must move in the direction of the force and move over a distance.