(i) Give the expression for mechanical advantage of an inclined plane in terms of the length of an inclined plane.
(ii)Name a common device where a gear train is used.

Hint: (i) The mechanical advantage of an inclined plane determines the relationship between the slope length and the inclined plane height.
(ii) A gear train consists of a combination of two or more gears, mounted on spinning shafts, for torque or power transmission.

Complete step by step answer:
(i) An inclined plane, also known as a ramp, is a smooth, angled support surface with one end higher than the other used as an aid to lift or lower a load.It takes less power to drive an object up an inclined plane than to lift it straight up, at a cost of raising the distance pushed.

The mechanical advantage can be determined using the formula:
\[{\text{Mechanical advantage = }}\dfrac{{{\text{Slope}}\;{\text{Length}}}}{{{\text{Height}}}}\]
\[M.A. = \dfrac{l}{h}\]

Here, \[M.A.\] is mechanical advantage
\[l\] is slope length
\[h\] is inclined plane height

(ii) A gear train is a mechanical structure that is shaped by mounting gears on a frame such that the gears' teeth engage. The gear teeth are constructed in such a way that the number of teeth on a gear is equal to the radius of its pitch circle and the pitch circles of meshing gears roll without sliding on each other.

A clock or watch is a widely known device which uses a gear train.

Note:
(i) In this question we are asked to give the expression for mechanical advantage of an inclined plane only. The mechanical advantage can be demonstrated by the conservation of energy in terms of the distance travelled.
(ii) Gear trains can be used in various objects depending on their function, but the simplest form is that of a clock or watch.