Answer:
3.6 m
Explanation:
let x = horizontal distance between emily and allison should be for allison to catch the ball
Find horizontal speed of the ball
vx = 12 sin 30 = 12 x 0.5 = 6 m/s
To find time taken, we will use vertical values of the ball motion
Initial velocity in vertical direction
u = 12 cos 30 = 10.392 m/s
let a = g = 9.8m/s2
Use equation of motion
s = ut +1/2at^2
s = vertical distance = 8
8 = (10.392)t + (1/2)(9.8)t^2
8 = (10.392)t + (4.9)t^2
4.9t^2 + 10.392t - 8 = 0
Using formula of quadratic or calculator, we'll find
t = 0.6 and t = -2.72
We pick t=0.6s since it's not logical time in negative
Assuming no air resistance or external forces, the ball will move 6m/s horizontally. Hence using the formula of speed
speed vx = distance x / time
x = (vx)(t)
= 6 x 0.6
= 3.6 m
