posted by Elisa .
A quarterback throws a football toward a receiver with an initial speed of 21 m/s at an angle of 30° above the horizontal. At that instant, the receiver is 12 m from the quarterback. In what direction and with what constant speed should the receiver run in order to catch the football at the level at which it was thrown?
a. The receiver should run in the direction the football is traveling.
b. The receiver should run in the direction opposite to that in which the football is travelling
what constant speed should the receiver run in order to catch the football at the level at which it was thrown?
Using d = (V^2/g)sin2µ
the distance the football travels derives from d = (21^2/9.8)sin(60) = 38.97 m.
The time it will take the ball to reach the receivers hands derives from Vf = Vo - gt or 0 = 21sin60 - 9.8t making t = 1.85 sec.
Consequently, the receiver should run away from the quarterback at a speed of (38.97 - 12)/1.85 = 14.58m/s.