Mechanical advantage has no unit, why?
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.
How simple machines makes our work easier???
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:
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, they can carry more bricks at the same time. Also, they don't have to carry the bricks on their head rather, they just need to push the wheel-barrow.