Question

a tennis ball is hit vertically upwards with a velocity of 20m/s.find the time taken for the ball to reach its highest point

Answer 1

$$v=v_0+gt,$$ $$0=v_0+gt,$$ $$t=-\dfrac{v_0}{g}=-\dfrac{20\ \dfrac{m}{s}}{-9.8\ \dfrac{m}{s^2}}=2.04\ s.$$