SCIENCE

Heat - Expansion
and contraction

NAME : JOTHISHVARMAA
CLASS : 5 VETRI
SUBJECT : SCIENCE
TEACHERS NAME : D.VELOO

Heat is the form of energy that is transferred
between systems or objects with different temperatures
(flowing from the high-temperature system to the low-temperature system).
Also referred to as heat energy or thermal energy.
Heat is typically measured in Btu, calories or joules.
Heat flow, or the rate at which heat is transferred between systems,
has the same units as power: energy per unit time

HEAT

IS A FORM ENERGY MAKE THINGS WARM

EXPANSION
AND

CONTRACTION

EXPANSION

 The presses in which the volume of a substance increases with the increase in
temperature is termed as expansion.

 Matter increases in volume when there is an increase in temperature.

 The volume increases the most in case of games.

 When something expands; it takes up more space.

 Exception: Water expands when cooler or frozen and contracts when warmed or
heated.

Example 1- Electric cables expand in summer
season.

Example 2-Hot air balloon
*Hot air balloon flies in the air because of the hot air
present inside it. Due to this hot air , balloon expands.

CONTRACTION

*The proses in which the volume of the substance decreases in the temperature is
termed as contraction.

Example 1- Electric cables contract in winter season. Example 2 - Hot air balloon.
 When something contracts ; it shrinks .
Hot air balloon deflates
(shrinks) because of the cold air in the atmosphere.
Due to this cold air, balloon contracts.

 When a substance absorbs or loses heat energy, the movement
of its particles is affected, which causes its volume to change.

 Solids, liquids and gases all expand when heated, due to the
increased movement of their particles.

 Solids, liquids and gases all contract when cooled, due to the
decreased movement of their particles.

 Temperature changes affect the volume of gases the most and
the volume of solids the least.

 There are many practical and safety considerations associated
with the expansion and contraction of matter due to
temperature changes.

Expansion and Contraction of Solids

 When substance expand or contract, the particles stay the same.
 Only the space between the particles changes .
 The particles is the solid vibrate more when it is heated thus take that more

roomExpansion.
 Similar to liquid and gases when heated.

Expansion and Contraction of Liquids

 When the liquid is heated, the molecules have more energy and move more vigorously.
The moment of the molecules overcome the force of attraction between the
molecules , allowing them to move freely. Thus, the volume of the liquid increases.

Expansion and Contraction of Gases

Expansion of gaseous

 When the gas is heated, the molecules gain more energy and move faster and
further apart. This courses the volume to increase.

Contraction of gaseous

 At a lower temperature, molecules have move slower and have less energy.
They are closer together closing the volume to decrease.

 Some materials expand on heating and some contract on cooling. Heating makes the particles (that form
the material) expand or become loose. Cooling makes the particles (that form the material) contract or
become tight.

 The amount of expansion differs in solids, liquids, and gases. Gases expand the most while solids expand the
least

Expansion in solid Expansion in liquids Expansion in gases

Railway tracks consist of two parallel metal rails Water expands on heating. Take a glass filled with If you keep an inflated balloon in the sun for
joined together. Small gaps, called expansion water to its brim. Pour the water into a container some time, what will happen? It will grow in size
gaps, are deliberately left between the rails as and heat It (do not boil). Now try to pour the water as the air inside it expands on taking heat from
there is an expansion of the rails in hot weather. back into the same glass. The water overflows. the surroundings.

Expansion gaps in railway tracks

 Cooling does the opposite of heating. Cooling causes a material to contract. Solids contract the
least while gases contract the most. Table lists some examples of contraction.

Contraction in solids Contraction in liquids Contraction in gases

If we hold a very hot glass tumbler under cold We observed that water expanded on heating. If an inflated balloon is tied at the mouth of a
water, it cracks. This is because the outer Can you say what will happen if the water is bottle and the bottle is placed in ice-cold water,
surface of the glass comes in direct contact with allowed to cool down and then poured back into what will happen? The balloon will shrink in size,
cold water and contracts more as compared to the glass? Would it still overflow? No. This is as the air inside the balloon contracts on cooling.
the inner surface. because of contraction.

The expansion and contraction of materials can also cause problems.

Bridges expand in the summer heat and need special joints to stop
them bending out of shape.

Volleyballs and basketballs left out in the cold become smaller and
softer because of the contraction from the air inside

THANK YOU`