"A particle of mass m moves in a straight line, so that at time t the particle has a displacement x measured from an origin O. The force acting on the particle is Fsin(ωt), where t is time, and F and ω>0 are constants.
(i) Write down the equation of motion for the particle.
Solution: mx ̈ = sin(ωt)"
My answer was mx ̈ = Fsin(ωt) but I don't see why the constant F disappears.
Thanks