Question

A body freely falling from a height h describes 7h/16 in the last second of its fall .the height h is (g=10ms^-2)

Answer 1

Answer:

45 m

Explanation:

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 - 7h/16 = (0 × T) + 0.5g(T - 1)²

9h/16 = 0.5g(T - 1)² .......(2)

Divide equations (1) and (2)

h / (9h/16) = 0.5gT² / [0.5g(T - 1)²]

16/9 = [T / (T - 1)]²

4/3 = T / (T - 1)

4T - 4 = 3T

T = 3 seconds

Substitute T = 3 s in equation (1)

h = 0.5gT²

= 0.5 × 10 m/s² × (3 s)²

= 45 m

Answer 2

45 m

hope it helps you..............................