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A boy jumps off a high diving board above a swimming pool. Halfway between the board and the water he tosses a ball up-ward. Ignoring air friction, the instant after the ball leaves his hands the vertical component of the acceleration of the ball (A) is positive, but then decreases through zero to -9.8 m/s 2 . (B) is zero, but then decreases to – 9.8 m/s 2 . (C) is between zero and -9.8 m/s 2 , but then decreases to -9.8 m/s 2 .

A boy jumps off a high diving board above a swimming pool. Halfway between the board and the water he tosses a ball up-ward. Ignoring air friction, the instant after the ball leaves his hands the vertical component of the acceleration of the ball
(A) is positive, but then decreases through zero to -9.8 m/s2.
(B) is zero, but then decreases to – 9.8 m/s2.
(C) is between zero and -9.8 m/s2, but then decreases to -9.8 m/s2.

Grade:upto college level

2 Answers

Deepak Patra
askIITians Faculty 471 Points
9 years ago
The correct option is: (A) is positive, but then decreases through zero to -9.8m/s2.
Assume that the boy tosses up the ball by imparting a vertical initial acceleration of magnitude a in the upward direction. If the magnitude of a is greater than g, the ball would have an initial positive acceleration.

As the magnitude of a would decrease over time and become zero, the net acceleration of ball would also decrease, pass through zero and eventually reach to . – 9.8 m/s2
Therefore, the correct option is (a), while the rest are ruled out.
Chayan
13 Points
one year ago
The answer I think should be (D) is -9.8 m/s^2. This is because the ball is given an initial velocity when tossing up. But the acceleration remains g.

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