A block and tackle has 2 pulleys in both the top and bottom blocks. Determine the displacement ratio, mechanical advantage and the efficiency when a load of 630N is lifted by an effort of 180N.
To determine the displacement ratio, we need to count the number of ropes supporting the load (the tension in the ropes changes depending on the direction of motion). In this case, there are 4 sections of rope supporting the load, leading to a displacement ratio of 4.
The mechanical advantage is calculated by dividing the load force by the effort force:
MA = Load force / Effort force
MA = 630N / 180N
MA = 3.5
The efficiency of the block and tackle system can be calculated using the formula:
Efficiency = (MA / displacement ratio) x 100%
Efficiency = (3.5 / 4) x 100%
Efficiency = 87.5%
Therefore, the displacement ratio is 4, the mechanical advantage is 3.5, and the efficiency is 87.5%.