plz explain this to me

- Mechanical advantage reduces gradually due to the weight and friction of the moving parts of a machine.

- Whereas, the velocity ratio of a machine always remains constant.

- This is the reason why mechanical advantage in a practical machine is always less that velocity ratio.

- Another reason is that the efficiency of a machine is given by the ratio of mechanical advantage to velocity ratio.

- Thus, if mechanical advantage is equal to velocity ratio, it will mean that the machine is 100% efficient which is practically impossible.