Question

A body projected vertically up with a velocity of 10 m/s reaches a height of 20 m. If it is projected with a velocity of 20 m/s, then the maximum height reached by the body is:

विकल्प

• 20 m

• 10 m

• 80 m

• 40 m

Answer 1

80 m
Explanation:
Initial velocity = u = 10 m/s
Height = Distance = S = 20 m
At highest point, Final velocity = v = 0
Acceleration = (a) = ?

Case − I
v² − u² = 2aS
(0)² − (10)² = 2a (20)
a = `-100/40` = −2.5 ms⁻²

Case – II
u = 20 m/s; v = 0
a = −2.5 ms−2; S = h /
v² − u² = 2aS
(0)² − (20)² = 2(−2.5)h
h = `400/5` = 80 m