A block and tackle having a velocity ratio of 5 is used to raise a load of 400N through a distance of 10m. If the workdone against friction is 100J. Calculate
1. Efficiency
2. The effort applied
Am finding it difficult to answer.
400 N * 10 m = 4 kJ ... work to raise the load ... output
a v.r. of 5 , means that the input line is pulled ... 5 * 10 m
the input work is ... 4 kJ + 100 J = 4.1 kJ
efficiency = output / input = 4 / 4.1
applied effort = 4.1 kJ / 50 m = ? N
To calculate the efficiency of a block and tackle system, we first need to calculate the useful work done and the total work done.
1. Useful work done:
The useful work done is the work done on the load. We can calculate it using the formula:
Useful work = Load × Distance
= 400N × 10m
= 4000 J
2. Total work done:
The total work done is the sum of useful work and work done against friction. We are given that the work done against friction is 100 J, so:
Total work = Useful work + Work against friction
= 4000 J + 100 J
= 4100 J
Now, we can calculate the efficiency:
Efficiency = (Useful work / Total work) × 100
1. Efficiency = (4000 J / 4100 J) × 100
= 97.56%
The efficiency of the block and tackle system is approximately 97.56%.
To calculate the effort applied, we can use the equation for the velocity ratio of a block and tackle system:
Effort / Load = Velocity Ratio
Given that the velocity ratio is 5, and the load is 400 N, we can rearrange the equation to solve for the effort:
Effort = Velocity Ratio × Load
= 5 × 400 N
= 2000 N
So, the effort applied in the block and tackle system is 2000 N.