Philip P. answered • 10/04/18

Effective and Patient Math Tutor

The key point here is that velocity is a vector. Hence it has a horizontal speed (v) and a vertical speed (u) that are independent. So how long will it take the ball to fall 100 m?

d = (1/2)gt²

100 = (1/2)(9.8)t²

20.41 = t²

4.52 = t

So horizontally, the ball moves at a constant velocity, v, for t = 4.52 sec:

d = vt

54 = v(4.52)

11.95 m/s = v --> This is the speed at which the ball was thrown

The vertical speed of the ball is:

u = gt

u = (9.8)(4.52)

u = 44.3 m/s

The ball's total speed is:

V = √(v²+u²)

V = √(11.95²+44.3²)

Use your calculator to get the answer (in m/s).