Suggest ways to increase the sensitivity of a thermometer, minimize friction, and define the center of gravity.

To increase the sensitivity of a liquid-in-glass thermometer, the liquid column should show a larger change in length for a small change in temperature. This can be achieved by:

• Using a liquid with a high coefficient of thermal expansion.
• Using a large bulb to hold more liquid, so a given temperature change results in a larger volume expansion.
• Using a narrow bore (capillary tube), so that a small volume expansion causes a significant rise in the liquid column.
• Using a thin-walled glass bulb to allow heat to transfer quickly to the liquid.

One means of increasing the sensitivity is to use a narrow bore (capillary tube).

Friction between solid surfaces can be minimized by:

• Lubrication: Applying a layer of oil, grease, or graphite between the surfaces.
• Polishing surfaces: Making the surfaces smoother to reduce interlocking irregularities.
• Using ball bearings or rollers: Converting sliding friction into rolling friction, which is generally lower.

One method of minimizing friction between solid surfaces is lubrication.

The center of gravity of a body is the imaginary point where the entire weight of the body appears to act.