In cases where pulley moves along with the blocks connected on both sides, we can say the displacement of the pulley is the average of the displacement on both sides of the pulley (Fig. 7).
If one end of the string is connected with fixed end, the displacement of that end can be considered as zero.
Applications of the pulley constraints
- As pulley 1 is fixed, hence the displacement should be zero (Fig. 8). If the displacement of block A is xA (down), then the displacement of other end should be xA (up).
- Displacement of block B = Displacement of pulley 2
- As pulley 1 is fixed,
- For pulley 2