In physics, a force is any external effort make thing change.
The Force formula
Force: F=M*A
Mass: M=F/A
Acceleration: A=F/M
where, m = Mass, a = Acceleration
For example, if Force = 36 N, Acceleration(a) = 3 m/s2, then Mass(m) = F/a = 36/3 = 12kg.