1.	When the blocks are in motion, the tension in the string will always lie between the weight of the two blocks. Explain this.

2.

When the mass of the pulley is zero, what determines the acceleration of the system? The difference between the mass of the two blocks is one factor, and g, the acceleration due to gravity, is another. What else (if anything) determines the acceleration? Compare the acceleration of the system in two cases where the masses differ by 1 kg, first when one mass is 4 kg and the other is 5 kg, and then when one mass is 1 kg and the other is 2 kg. Is the acceleration the same?

3.	When the mass of the pulley is zero, the tension is the same in both parts of the string. When the pulley has a mass, however, the tension is different in the two parts of the string. Why does this happen?