PHYSICS [2 Mark Question Answer]

When liquid is heated, both liquid and container undergo a change in their volume. The intermolecular force of attraction in liquids is weaker as compared to solids. If the liquid is heated, molecules will start to vibrate faster because of their weak intermolecular force between each other. When molecules are vibrating faster, they need more space to occupy, which leads to the expansion of liquids.

A fire alarm is a unit made of several devices, which uses visual and audio signalization to warn people about a possible fire, smoke, or carbon monoxide occurrence in the area of coverage. Fire alarms are usually set in fire alarm systems to provide zonal coverage for residences and commercial buildings.

The telephone and telegraph wires are metallic wires. The metallic wires undergo thermal expansion in summer and sag down. Then the chances of getting contacted with other wires during the storm and causing a serious breakdown are high. To avoid breakdowns, telephone and telegraph cables are laid loosely to allow contraction in winter. The wires will be laid tightly during winters for allowing them to expand in summer.

The girders used to support the bridges will expand on heating and contract on cooling. If the girders are attached to the walls of the pillars, the walls will get damaged because of the expansion and contraction of the girders. The girders are fixed on the rollers leaving a small space in between for expansion or contraction.

These gaps which are of the order of a few millimeters, are provided to allow room for the rails to expand the rise in temperature due to the atmospheric temperature as well as the friction caused by running of train. All materials expand when heated and contract when cooled.

The iron rims will undergo thermal expansion in the summer season. Thermal expansion is the expansion happening in substances when heated. If the iron rims are expanding, then they will get loosened from the wooden wheel. To avoid this kind of situation iron rims are mounted to the wooden wheel in a way that iron rims are having lesser diameter than the wheel to hold them tightly after expansion also.

The expansion of matter by absorption of heat energy is known as thermal expansion. Thermal expansion can be categorized into three types: 1) Linear expansion 2) Superficial expansion 3) Cubical expansion. Linear expansion: The increase in the length of matter by the absorption of heat energy.

Thermal expansion is the tendency of matter to change in shape, volume, and area in response to a change in temperature. Temperature is a monotonic function of the average molecular kinetic energy of a substance.