An attacker at the base of a castle wall 3.60 m high throws a rock straight up with speed 4.00 m/s from a height of 1.60 m above the ground.
(a) If so, what is its speed at the top? If not, what initial speed must it have to reach the top?
(b) Find the change in speed of a rock thrown straight down from the top of the wall at an initial speed of 4.00 m/s and moving between the same two points.
(a) The rock won't reach the top of the castle.
v = [2*(9.8)*(2)]1/2 = 6.264 ms-2
(b) 4*t + 0.5*9.8*t2 = 2
t = 0.35 sec
Final velocity, v = 4 + 9.8*0.35 = 7.43 ms-1
Change in velocity = 7.43 - 4 = 3.43 ms-1