Question

A body freely falls from a height h describes 9h/25 in the

Answer 1

Answer:

h = 122.5 m

Explanation:

Full Question:

A body freely falls from a height h describes 9h/25 in the last 1 sec then value of h is?

Let total time taken be "T" seconds

Use equation of motion

• S = ut + 0.5at²

For total fall

h = (0 × T) + (0.5gT²)

h = 0.5gT² .......(1)

For the time t = T - 1 seconds

h - 9h/25 = (0 × T) + 0.5g(T - 1)²

16h/25 = 0.5g(T - 1)² .......(2)

Divide equations (1) and (2)

h / (16h/25) = 0.5gT² / [0.5g(T - 1)²]

25/16 = [T / (T - 1)]²

5/4 = T / (T - 1)

5T - 5 = 4T

T = 5 seconds

Substitute T = 5 s in equation (1)

h = 0.5gT²

= 0.5 × 9.8 m/s² × (5 s)²

= 122.5 m

Answer 2

the particle is dropped then u = 0

As we all know that g = 9.8 m/s^2.

Then from the third equation of motion=

S = ut+1/2 gt^2

S = ½ gt^2

where t is the total time taken

Distance covered in (t-1) sec = h -9h/25 = 16h/25

Solving (1.) and (2.)

T = 5s

Substituting the value of t in eq. 1

S = ½ *9.8 *25

S = 122.5 m