A boy and his skateboard of total mass 60kg coasts down a frictionless ramp at an angle of 30º to the horizontal. (a) Calculate the normal force acting on the boy and skateboard.
(b) Calculate the net force acting on the boy and skateboard.

Panel bc in fig. p2.76 is semi-circular, with the 3 meter radius and horizontal straight edge through point b. compute (a) the hydrostatic force of the water on the panel, (b) its center of pressure, and (c) the moment of this force about point b. assume atmospheric pressure on the dry side of the panel