A stone thrown vertically upwards takes 3 seconds to attain maximum height, calculate
(i) initial velocity of stone
(ii) maximum height attained by the stone
Let,
u = Initial velocity of stone
H = Maximum height attained by the stone
v = final velocity at maximum height = 0
t = time taken to attain maximum height = 3 s
a = -g = acceleration due to gravity
(i) We know that,
v = u + at
0 = u – g × 3
u = 3g = 3 × 9.8 ms-2
u = 29.4 ms-1
(ii) From the equations of motion, we know that,
H = 132.3 m