A load of 600N is lifted by a lever by using the effort of 300N. If load distance and effort distance are 20 cm and 60 cm respectively. Calculate the mechanical advantage, velocity ratio and efficiency of the lever.

Mechanical advantage (MA) is theratio of Load to Effort. Both load and effort are forces, i.e., MA is the ratio of two same physical quantities. So, it has no unit.

Though there is no gain in mechanical advantage by using a single fixed pulley it is used in practice, it is because of the following reasons:

• It is simpler to learn and use.
• The entire weight of the person is used in doing work.
• It is easier to construct.
  
  

The efficiency of a simple machine is 90% means that only 90% of the applied effort is converted into useful work. The rest 10% is used in overcoming frictional force and other forces during the operation of machine.

Simple machines are designed to make human works easier, faster and more comfortable than the traditional days. Following are the ways in which simple machines make our work easier:

• By multiplying our applied effort.
• By increase the rate of doing work.
• By transferring the applied effort from one end to the other end.

Let us just imagine the life of a labour. When there was no wheel-barrow, they would have to carry 7-8 bricks on top of their head which is painful. With the use of wheel barrow,...