Q:

A rugby player passes the ball 7.75 m across the field, where it is caught at the same height as it left his hand. At what angle was the ball thrown if its initial speed was 12.0 m/s, assuming that the smaller of the two possible angles was used?

Accepted Solution

A:
Given that the "launch" and "impact" heights are the same, we shall use the range equation and the time of flight equation.
(a)(b)range x=V²sin (2θ)/g
7.75m=(12 m/s)sin (2θ)/ 9.8m/s²
sin (2θ)=0.5274
hence:
2θ=arcsin 0.5274=31.83°
or 2θ=180-31.83=148.17°
hence the smaller angle will be:
31.83/2=15.915~15.92°
and the larger angle will be:
148.17/2=74.085°