Question

A body is dropped from a height H. It reaches the ground in time 5s. Find H
1) 15m
2) 125m
3) 170m
4)10m​

Answer 1

Answer:

125m

Explanation:

by second equation of motion

s= ?

u=0

t= 5s

g=10m/s square

s= 1÷2×10×25^2

s= 125 m

Answer 2

Given:

A body is dropped from a height H. It reaches the ground in time 5s.

To find:

Value of H ?

Calculation:

• Since the question says that the object was dropped, it means that the initial velocity is zero.

Now, applying Equation of Kinematics:

$H = ut + \dfrac{1}{2} g {t}^{2}$

$\implies \: H = 0(5) + \dfrac{1}{2} \times 10 \times {5}^{2}$

$\implies \: H = 0 + \dfrac{1}{2} \times 10 \times 25$

$\implies \: H = \dfrac{1}{2} \times 10 \times 25$

$\implies \: H = 5 \times 25$

$\implies \: H = 125 \: metres$

So, value of H is 125 metres.