Question

40. MIJ 07/P1/Q8
A stone is dropped from the top of a tower of height 40m. The stone falls from rest and air resistance is negligible.
What time is taken for the stone to fall the last 10m to the ground?
A 0.38s
B 1.4s
C 2.5s
D 2.95

Answer 1

Answer:

B. 1.4s

Explanation:

u = 0 m /s

s = 40 m

a = g = 9.8 m/s^2

t = ?

We have to find time we stone in 10m above from ground so:-

s = 10m

By equation

s = ut + 1/2 × a × t^2

Put the value

10 = 0 × t + 1/2 × 9.8 × t^2

10 = 4.9 × t^2

_/10 / 4.9 = t

1.42 = t

.: 1.4s to reach ground when stone above 10m from ground.