During a test crash an airbag inflates to stop a dummy's forward motion. the dummy's mass is 75kg. if the net force on the dummy is 825n toward the rear of the car , what is the dummy's deceleration.

Why does the equilibrium position of the spring change when a mass is added to the spring? will the mass oscillate around the new equilibrium position of the spring or the previous position without a mass attached to the spring? if the equilibrium position of the spring changes by 20 cm (assuming no initial mass) when a mass is added to the spring with constant 4.9 kg/s^2, what is the mass of the object attached to the spring?