Question

a body falling from rest was observed to call through 78.4 m in 2 second. How much time it have been
falling before it was observed

Answer 1

Given

i. Motion from B to C

BC = 78.4 m, is the displacement in 2 s

From

S=ut+1/2at^2

Where S=78.4m, a=9.8, t=2 and u is initial velocity during the observation = velocity at B.

Substituting, u=29.4m/s

ii. Motion from A to B

Intial velocity = velocity at A = 0

Final velocity = velocity at B = 29.4m/s

From v= u+at

29.4= 0+9.8t

Or t=3s.

Therefore body had been traveling for 3s before it was observed

Answer 2

Explanation:

3 sec is your answer please ✔️ it