Question

What is the magnitude and direction of the velocity and the acceleration of an object thrown into the air at the instant the object reaches its maximum height?

Answer 1

An object thrown into air moves only under the action of gravitational force exerted on it by earth and thus undergo an acceleration equal to the acceleration due to gravity and always act vertically downward whether the object is moving up or down in the air. The velocity of a body thrown in the air continuously go on decreasing till at the highest point it becomes zero and then the body starts moving downward.

Thus for a body thrown into air attaining highest point in its fly, the magnitude of velocity becomes zero and act in downward direction. Similarly acceleration at the highest point will have a magnitude = 9.8 m/s^2 and acts in the vertically downward direction.