- Natural and man-made changes
- Periodic and non-periodic changes
- Desirable and undesirable changes
- Reversible and irreversible changes
- Physical and chemical changes
- Expansion and contraction of materials
- Expansion and contraction of solids
- Expansion and contraction of liquids
- Expansion and contraction of gases
- Applications of expansion and contraction
PHYSICAL AND CHEMICAL CHANGES
Physical Changes:
• Those changes in which no new substance is formed are called physical changes.
• During physical changes, the properties of a substance remain the same.
• Many times they are temporary and can be reversed. Melting of ice is one such change.
• There are some changes which are physical but irreversible. For example:
Read More...EXPANSION AND CONTRACTION OF MATERIALS
• Different materials expand or contract at different rates at different temperatures.
• Like: Heating water can change it to steam.
• Thus, heating a material can change it.
Read More...EXPANSION AND CONTRACTION OF SOLIDS
• People who design structures such as buildings and bridges are very careful about the materials they use.
• They choose materials that will not break when temperatures change.
• A building project often requires two or more materials.
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