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A 35 g steel ball is held by a ceiling-mounted electromagnet 4.0 m above the floor. A compressed-air cannon sits on the floor, 4.4 m to one
Question
A 35 g steel ball is held by a ceiling-mounted electromagnet 4.0 m above the floor. A compressed-air cannon sits on the floor, 4.4 m to one side of the point directly under the ball. When a button is pressed, the ball drops and, simultaneously, the cannon fires a 25 g plastic ball. The two balls collide 1.2 m above the floor. What was the launch speed of the plastic ball?
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Physics
3 years
2021-08-15T20:38:22+00:00
2021-08-15T20:38:22+00:00 1 Answers
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Answer:
7.9 m/s
Explanation:
When both balls collide, they have spent the same time for their motions.
Motion of steel ball
This is purely under gravity. It is vertical.
Initial velocity, u = 0 m/s
Distance, s = 4.0 m – 1.2 m = 2.8 m
Acceleration, a = g
Using the equation of motion
Motion of plastic ball
This has two components: a vertical and a horizontal.
The vertical motion is under gravity.
Considering the vertical motion,
Initial velocity, u = ?
Distance, s = 1.2 m
Acceleration, a = –g (It is going up)
Using the equation of motion
Substituting the value of t from the previous equation,
Taking g = 9.8 m/s²,
This is the vertical component of the initial velocity
Considering the horizontal motion which is not accelerated,
horizontal component of the initial velocity is horizontal distance ÷ time.
The initial velocity is