If motion of a particle of mass (m) is given by y=ut+1/2gt^2 (square).find force acting on it

Answer 1

I assume that u and g are constants (in fact initial velocity and gravity)

dy/dt = speed = u + g t

d^2y/dt^2 = acceleration = g

F = m a
so
F = m g

Answer 2

Not too bad

Answer 3

Wrote

Answer 4

dy/dt = speed = u + g t

d^2y/dt^2 = acceleration = g

F = m a
so
F = m g