A block and tackle system has the velocity ratio 3. Draw a labelled diagram of the system indicating the points of application and the directions of load L and effort E. A man can exert a pull of 200 kgf.

(a) What is the maximum load he can raise with this pulley system if its efficiency is 60%?

(b) If the effort end moves a distance 60 cm, what distance does the load move?

You are given four pulleys and three strings. Draw a neat and labelled diagram to use them so as to obtain a maximum mechanical advantage equal to 8. In your diagram mark the directions of load L, effort E and tension in each strand. What assumptions have you made to obtain the required mechanical advantage?

You are designing a block and tackle system for a construction site with following data set: load to be lifted = 3000 N. Maximum effort to be applied = 400 N and efficiency of system = 75%. Calculate :

(a) The minimum V.R. required.

(b) The minimum number of pulleys required.

(c) Suggest a practical pulley arrangement.

To lift a heavy load of 600 N vertically, load is attached to a block and tackle system of 4 pulleys [2 pulleys each]. The free end of rope is tied to a uniform lever of length 2 m pivoted at one end at a distance of 0.5 m from the fulcrum. A man applies effort E at the other end of lever. Assume the system to be ideal.

Calculate :

(a) The mechanical advantage of the pulley system and tension T to support the load.

(b) The least value of effort E applied to lift the load.

(c) Is there any advantage of attaching a lever to the pulley system?