Question

A golfer has to hit a ball over a tree that is 12.0 meters high from 40.0 meters away. The ball is hit with speed v at an angle (-) to the horizontal. Neglect any effect due to air. The golfer hits the ball with an initial velocity 30 degrees to the horizontal. Calculate the speed that must be given to the ball for it to just clear the tree.
*Note the ball DOES NOT have a vertical velocity of 0m/s when it passes over the tree.

Answer 1

well, you know that

y = -g/(2v^2) sec^2 θ x^2 + tanθ x
= -4.9(4/3)/v^2 x^2 + 0.5773 x

If it just clears the tree (not brushing any branches), then y(40) = 12, so

12 = -6.5333/v^2 (40)^2 + 0.5773(40)
v = 30.7 m/s

Answer 2

Thank you!