Skateboard Reference Frames?

A Physics student is riding on a skateboard traveling along a straight horizontal road at a constant speed of 2 m/s. The student throws a ball into the air that she observes to rise straight up vertically. A man, who is sitting on a park bench nearby, observes the ball on a trajectory that makes an initial angle of 72° with respect to the horizontal road.





2) How high does the ball rise?





a) 0.27 m


b) 1.51 m


c) 1.93 m


d) 2.87 m


e) 8.99 m

Skateboard Reference Frames?
Vertical velocity = (2m/s) sin(72degrees) / cos(72degrees)





Vertical velocity =(2m/s) tan(72degrees) = 6.155m/s





Time to reach peak = Vertical velocity / Gravity





Time = (6.155m/s) / (9.81m/s^2) = 0.627s





Average velocity = (vf+vi)/2 = (0m/s+6.155m/s) / 2


= 3.078m/s





Vertical distance = Average vertical velocity x time





= 3.078m/s x 0.627s





= c) 1.93m