A boy throws a ball of mass 0.24 kg straight upward with an initial speed of 24 m/s. When the ball returns to the boy, its speed is 15 m/s. How much work (in J) does air resistance do on the ball during its flight

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?