Page 63 - York Global Science 6 - Physical Science

Physical Science

Let’s Understand

Find out how different substances change when
they are heated.

Decide if the changes are physical changes or
chemical changes.

World of Science

Materials that expand and contract when they are heated can cause
problems.

Engineers make bridges with expansion joints so
that when a bridge is heated by the Sun and the
metal expands, the bridge stays the right shape

and does not bend.

Railway tracks also have spaces between them
so that they can expand in the heat and stay the
right shape.

Remember!

Changes of state that are caused by heating can be reversed by cooling.
Different materials change state at different temperatures.

Let’s Reflect

1 Name three ways that materials can change when they are heated.

2 When are these changes useful?
3 When might they cause problems?

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