1. The problem statement, all variables and given/known data We have a pendulum in thermal balance with the surroundings - no damping. We measure the speed of the pendulum. The accuracy of each speed measurement is known. How does the accuracy of the speed change, if we decide also measure the position of the pendulum with accuracy 10% of the amplitude? 2. Relevant equations Just anything you can think of. 3. The attempt at a solution Believe me, I would be more than happy to show anything. It has been quite some time since I first came across this problem but I still have no idea how to continue.