Some life-forms move so slowly that their movement cannot be detected by normal observation. The best way to determine any movement is by placing a mark at some point, and observing any change in position from it. Why is this true?

Apossible explanation for a set of facts that can be tested by further investigation is called

The 10-kg double wheel with radius of gyration of 125mm about o is connected to the spring of stiffness k = 600 n/m by a cord which is wrapped securely around the inner hub. if the wheel is released from rest on the incline with the spring stretched 225 mm, calculate the maximum velocity v of its center o during the ensuing motion. the wheel rolls without slipping

It is really hard for me right know