A 2.5 m rod of mass M= 4. kg is attached to a pivot .8m from the left end so that it can rotate vertically. At the left end of the rod is a small object with mass m=1.5kg. A spring with a spring constant k=90N/m is attached to the right end of the rod. The other end of the spring is attached to a vertical

Track with a mechanism that keeps the spring horizontal at all times. When the rod ishorizo tal
The spring is at it's equilibrium length. What is the angular acceleration of the rod when it is
At a 28 degree angle from the horizontal