- Which of the following five formulas represents the acceleration of the pulley system? You would then be given five different mathematical formulas, one of which is the correct formula. The test writers would not expect you to have memorized the correct formula, but they would expect you to be able to derive it.
- Which of the following is a way of maximizing the system’s acceleration? You would then be given options like “maximize M and m and minimize
,” or “maximize 
and m and minimize M.” With such a question, you don’t even need to know the correct formula, but you do need to understand how the pulley system works. The downward motion is due to the gravitational force on m and is opposed by the force of friction on M, so we would maximize the downward acceleration by maximizing m and minimizing M and 
- If the system does not move, which of the following must be true? You would then be given a number of formulas relating M, m, and
. The idea behind such a question is that the system does not move if the downward force on m is less than or equal to the force of friction on M, so 
.
These examples are perhaps less demanding than a question that expects you to derive or recall a complex formula and then plug numbers into it, but they are still difficult questions. In fact, they are about as difficult as mechanics questions on SAT II Physics will get.
