A poorly designed playground slide begins with a straight section and ends with a circular arc as shown in the figure below
A child starts at point P and slides down both sections of the slide. At some point on the circular arc, the normal force goes to zero and the child loses contact with the ramp.
Assuming the forces of friction are negligible, at what height from the ground will the child become airborne?
Answer in units of m.
I don't know where to start here!