We have a spring-mass system which oscillates in one dimension on a frictionless horizontal surface. We act an external force on the mass. F=kχo sin(ωt). Let x=Asin(ωt+φ),A>0 and ωο is the natural frequency of the system. a) What is the phase of the motion of the mass relatively to the phase of the external force when ω<ωο and when ω>ωο? b) What is the phase of the velocity relatively to the phase of the external force when ω<ωο and when ω>ωο? If ω<ωο the motion of the mass is in phase φ with the external force and the amplitude of the mass oscillation is greater than the amplitude of the wiggling. As the forcing frequency approaches the natural frequency of the oscillator, the response of the mass grows in amplitude. When the forcing is at the resonant frequency, the response is technically infinite. When the forcing frequency is greater than the natural frequency, the mass actually moves in the opposite direction of the motion, the response is out of phase with the forcing. The amplitude of the response decreases as the forcing frequency increases above the resonant frequency. I cannot think of anything else. Could anybody please tell me if I am close to the right answer?