A piece of stone is thrown vertically upwards. It reaches the maximum height in 3 seconds. If the acceleration of the stone be 9.8m/s2 directed towards the ground, calculate the initial velocity of the stone with which it is thrown upwards.
Final velocity v = 0 m/s
Gravity acceleration g = 9.8 m/s^2
time t = 3 sec
Then the calculate of initial velocity u from 1st equation of motion
v = u + gt
0 = u + 9.8 × 3
u = – 29.4 m/s
Negative sign shows direction of initial velocity is opposite the gravity acceleration.