A block and tackle system have the velocity ratio 3. A man can exert a pull of 200 kgf. What is the maximum load he can raise with this pulley system if its efficiency is 50%? [5 marks]
We know that when efficiency is 100% then,
Effort (E) = Loadn (number of pulleys)
⇒200=L3
⇒L= 600 kgf [2.5 mark]
When, efficiency is given as 50%.
So, Maximum load that can be raised
= 50100×600 = 300 kgf [2.5 mark1]