The mechanical advantage of an inclined plane is the ratio of the length of the plank to the vertical height of the load raised. Its value is greater than one. Therefore, an inclined plane acts as a force multiplier. Thus, it can be used to lift heavy loads.
Examples, If a heavy box needs to be loaded on a lorry, it is far easier to push it over an inclined plane than to lift up. Steeper the inclined plane, greater will be the effort required to push up the load.