Question

Naomi Osaka, a Japanese-African-American tennis player is the 2021 Australian Open Champion, and the first Asian tennis player in Women's Tennis Association (WTA) history to be ranked first in Singles. To celebrate her win, Naomi Osaka hits a ball into the stands at 40. m/s and at an angle 30.° above the horizontal. On its way down, the ball is caught by a spectator 12 m above the point where the ball was hit.
a) Calculate the time it takes the tennis ball to reach the spectator.

b) Calculate the ball's horizontal range (horizontal distance travelled).

Answer 1

Answer:

(a) t = 0.75 s

(b) d = 26 m

Explanation:

Height, h = 12 m

Angle, A = 30 degree

initial velocity, u = 40 m/s

(a) Let the time is t.

Use second equation of motion

 $h = u t + 0.5 at^2\\\\12 = 40 sin 30 t - 0.5 \times10 \times t^2\\\\12 = 20 t - 5 t^2\\\\5 t^2 - 20 t + 12 =0 \\\\t = \frac{20\pm \sqrt{400-240}}{10}\\\\t = \frac{20\pm 12.65}{10}\\\\t = 3.3 s, 0.75 s$

(b) d = u cos A t

d = 40 x cos 30 x 0.75 = 26 m