A stone is dropped from a certain height, distance covered by it in one second is:
(a) 4.9m
(b) 1m
(c) 10m
(d) 9.8m

d = 4.9 m

Explanation:

It is mentioned that a stone is dropped from a certain height. It is required to find the distance covered by it in one second.

The initial speed of the stone is equal to 0 as it was at rest. Let d is the distance covered by the stone.

Using second equation of motion :

Put u = 0 and a = g

So, the distance covered by it in one second is 4.9 m.

layer a is the exosphere and layer b is the thermosphere.   is the answer i think but i hope this .