Question

v=u+at rewrite for a free fall body

Answer 1

in free fall body
a = acceleration due to gravity . but in negative sign ( because this is directed in downward direction )
u = zero
we choose Reference level at highest point , and body moves downward so,
V is also negative

v = u + at
-v = 0 - gt
-v = -gt
v = gt

Answer 2

Free Fall:
A body is said to be free fall when only gravitational force acts on that body.

General equations of motion:
1. V=u+at
2.S=ut+1/2at²
3. V²-u²=2as

Important Points to Remember:
-->When a body is falling vertically downwards its velocity increases.
So g=+g =+9.8m/s²

--->For a free fall object:
initial velocity =u=0;
equation of motion will change as
V=0+gt ⇒v=gt
∴t=time descent=v/g=u/g[∵time of ascent= time of descent]
t=u/g ----------(1)

Second equation of motion:
h=0+1/2gt²
h=1/2gt² ----------(2)

third equation of motion:
As the object reaches ground its final velocity will be zero:
So V=0;
0²-u²=2gh
u=√2gh-----(3)