At the maximum height of an object in vertical motion, two things happen to acceleration and velocity:
Acceleration: At the maximum height, the acceleration due to gravity remains constant. In the absence of other forces, such as air resistance, the acceleration due to gravity is always acting downward and has a constant value of approximately 9.8 m/s^2 on the surface of the Earth. Therefore, at the maximum height, the acceleration due to gravity remains unchanged.
Velocity: At the maximum height, the velocity of the object becomes zero. This occurs because the object is momentarily at rest at the highest point of its trajectory before it starts descending. As the object moves upward, the acceleration due to gravity acts against its motion, gradually slowing it down. Eventually, the upward velocity decreases to zero at the maximum height. After reaching the maximum height, the object starts descending, and its velocity becomes negative as it accelerates downward due to gravity.
To summarize, at the maximum height of an object in vertical motion:
- The acceleration remains constant and is equal to the acceleration due to gravity.
- The velocity becomes zero before the object starts descending.