Physics
Name the pulley which has no gain in mechanical advantage. Explain, why is such a pulley then used?
Answer
The pulley that has no gain in mechanical advantage is a single fixed pulley.
A single fixed pulley is used only to change the direction of effort to be applied i.e. with its use the effort can be applied in a more convenient direction.
It is difficult to apply the effort upwards to lift a load up directly, but it becomes easier with the help of a fixed pulley, because the effort can be applied in the downward direction to raise the load up. Further to apply the effort downwards one can conveniently make use of his own weight also for the effort.
Related Questions
State whether the following statements are true or false.
(a) The velocity ratio of a single fixed pulley is always more than 1.
(b) The velocity ratio of a single movable pulley is always 2.
(c) The velocity ratio of a combination of n movable pulleys with a fixed pulley is always 2n.
(d) The velocity ratio of a block and tackle system is always equal to the number of strands of the tackle supporting the load.
What is a fixed pulley? State its one use.
What is a single movable pulley? What is its mechanical advantage in the ideal case?
Give two reasons why the efficiency of a single movable pulley is not 100%.