does ball take same time to go up and come down?

In the absence of air resistance, a ball will take the same amount of time to rise to its highest point as it will to descend from that point and return to the starting level. This is a fundamental principle in classical mechanics and is known as the symmetry of motion.

The key idea behind this principle is that the only force acting on the ball is gravity, which provides a constant acceleration directed downward. When the ball is thrown upward, it slows down due to gravity until it momentarily stops at the highest point of its trajectory. Then, as it descends, it accelerates downward. The magnitude of the acceleration remains constant throughout the motion.

As a result, the time it takes for the ball to reach its highest point (the ascent) is equal to the time it takes for the ball to descend from the highest point to the starting level (the descent). In both cases, the ball experiences the same acceleration due to gravity.

However, it's important to note that in the real world, factors like air resistance and other environmental conditions can affect the motion of the ball. These factors may lead to small differences in the time it takes for the ball to go up compared to coming down, but in most everyday situations, these differences are negligible.