A stone is thrown upwards with a velocity of 72 km/hr. If the air resistance is neglected, find the maximum height travelled by it.
Solution:
Initial velocity of stone (u) = 72 km/hr = 72 * 1000/3600 = 20 m/s
The stone is acted by constant downward acceleration equal to the acceleration due to gravity of earth, i.e, a = -g = - 10 m/s2
At maximum height, the velocity of the stone becomes 0 for a very short time so, final velocity of stone (v) = 0 m/s
To find: maximum height (H) = ?
Using equations of motion,
v2 = u2 + 2aH
or, 02 = (20)2 + 2(-10)H
or, 0 = 400 - 20H
or, 20H = 400
or, H = 400/20
So, H = 20 m
Hence, the maximum height...