Question

a stone is thrown downward with velocity 10 m/s from the roof of a building abd it reaches the ground with speed 40m/s.the height of the building would be
1)75 m
2)100m
3)125m
4)150m​

Answer 1

Answer:

u=10

v=40

a=10

v²-u²=2as

1600-100=2×10×s

1500=20s

=75m

Answer 2

Answer:

Here it is

Explanation:

v= 40m/s (Given)
u= 10m/s (As it is being dropped from a building and also given)
a = g = 10m/s (say)(As it is a condition of free fall)
h = (To be found out)

By using Newton's Third Equation of Motion
v²-u²=2gh (Equation used when object is in condition for free fall)
40²-10²=2×10×h
1600-100=20h
1500=20h
$\frac{1500}{20}$=h
75=h

Height of the building is 75m

Hence option 1) is correct