Question

(problem reference 2-1)
a tennis ball is shot vertically upward with an initial speed of 20.0 m/s. what is the magnitude of the acceleration of the ball when it is at its highest point?
3.13 m/s²
19.6 m/s²
9.80 m/s²
zero m/s²
4.90 m/s²

Explanation:

Step1: Identify the force acting on the ball

The only force acting on the ball throughout its motion (neglecting air - resistance) is gravity.

Step2: Recall the acceleration due to gravity

Near the surface of the Earth, the acceleration due to gravity $g$ has a magnitude of approximately $9.80\ m/s^{2}$. At the highest point of the ball's vertical motion, although its velocity is zero, the force of gravity still acts on it, causing an acceleration of $9.80\ m/s^{2}$ downward.

Answer:

$9.80\ m/s^{2}$