✔ 最佳答案
Converting to unit of m/s, initial velocity of the ball = 70/3.6 = 19.44 m/s
Also inclination of initial velocity = 30 deg.
Then, in the 10 s interval, distance travelled by the car = 194.4 m
With vertical height above Y = 194.4 sin 30 = 97.2 m
So, considering the vertical part of the projectile motion of the ball, we have:
(19.44 sin 30)T - 5T2 = -97.2 where T is the time of flight
9.72T - 5T2 = -97.2
5T2 - 9.72T - 97.2 = 0
T = 5.49 s
Thus, horizontal distance travelled, also the distance from the starting point to Y, is:
5.49 x 19.44 cos 30 = 92.4 m