What type of force can never do any work on an object

Ahypothesis is? close agreement by competent observers of observations of the same phenomena. a guess that has been tested over and over again and always found to be true. an educated guess that has yet to be proven by experiment. the long side of a right triangle. a synthesis of a large collection of information that includes guesses.

Need only answer if you think you know it

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?