Question

A stone reaches the ground in 5 Sec when dropped from certain height. If it becomes steady after 3 Sec while falling then falls again, time taken by it to reach the ground
A 6 Sec
C. 6.5 Sec
B. 7 Sec
D. 7.5 Sec​

Answer 1

Answer:

Hey mate , I think the answer is B) 6.5 second

Hope this helps you

Answer 2

Hello Dear,

◆ Answer -

(B) 7 s

◆ Explaination -

Total height of fall is -

s = u.t + 1/2 a.t^2

s = 0 × 5 + 1/2 × 10 × 5^2

s = 125 m

In first 3 s, stone will fall a distance of -

s1 = u.t1 + 1/2 a.t1^2

s1 = 0 × 3 + 1/2 × 10 × 3^3

s1 = 45 m

Stone is stopped at this point and dropped again. Now stone have to cover distance of 125-45 = 80.

s2 = u.t2 + 1/2 a.t2^2

80 = 0 × t2 + 1/2 × 10 × t2^2

80 = 5t2^2

t2^2 = 16

t2 = 4 s

Total time taken is therefore -

t' = t1 + t2

t' = 3 + 4

t' = 7 s

Thus, total time taken by the stone to fall is 7 s.

Hope this helps you...