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Delta Modern Language Schools
Science department
Grade 6
1st term 2024- 2025

►Bridges :

- Bridges are made up of steel (metal) and concrete.
- When bridges are exposed to hot weather, the temperature of
metal increases and the spaces between its molecules increase, so
the molecules of metal spread out and expand.
Expansion joints
- So, engineers use expansion joints to keep bridges safe from
buckling (bending) when they expand at high temperatures.

►Railroad tracks

- Railroad tracks are made of iron.
- Engineers leave small spaces between the railroad tracks to allow these tracks to
expand in hot weather without being bent to avoid train accidents.
Railroad tracks

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