Question

29. A base ball is thrown vertically upwards. At the maximum height
(A) the instantaneous speed is zero and the acceleration is 9.8 ms^-2, acting vertically downwards
(B) the instantaneous speed is zero and the acceleration is 9.8 ms^-2? , acting vertically upwards
(C) both the instantaneous speed and the acceleration are zero
(D) the instantaneous speed is finite but the acceleration is zero​

Answer 1

Answer:

(A) the instantaneous speed is zero and the acceleration is 9.8 ms^-2, acting vertically downwards

Explanation:

This is called the acceleration due to gravity and is usually denoted by the symbol g. An object that is thrown vertically upwards decelerates under the earth's gravity. Its speed decreases until it attains a maximum height, where the velocity is zero. Then it is accelerated uniformly downwards under gravity.

And we know that the gravitational acceleration is approximately 9.8 m/s^2 and, as it's constant. So, at maximum height, and at any height, the acceleration of the ball is equal to the gravitational acceleration.