Given the above wiggling, the force of the spring on the mass becomes F=−k(x−d)=−k[x−d0cos(ωFt)] since the length of the spring is the difference between the p...Given the above wiggling, the force of the spring on the mass becomes F=−k(x−d)=−k[x−d0cos(ωFt)] since the length of the spring is the difference between the positions of the left and right ends. Notice that if ωF<ω1, the motion of the mass is in phase with the wiggling motion and the amplitude of the mass oscillation is greater than the amplitude of the wiggling.