Review: renewable power and weathering
Wind, water and sunshine are renewable sources of energy. Wind and falling water turn turbines that spin generators. A dam stores water high up, and the Sun and the water cycle refill it. A dam has gains and costs. Sunlight can warm water in a solar cooker if we reflect it with foil, absorb it with a dark surface and trap the heat with a clear cover. We test materials fairly by changing one thing. In Unit 4 we learned that rock is broken into smaller pieces by weathering. Mechanical weathering only breaks it, as ice and roots do. Chemical weathering changes it, as rust and acid do. Erosion moves the pieces: gravity, rivers, waves, rain, wind and glaciers all carry sediment. Models such as chalk and vinegar help us study slow changes quickly.
| Source or process | What moves or changes |
|---|---|
| wind turbine | moving air turns blades |
| hydroelectric dam | falling water turns a turbine |
| solar cooker | reflect, absorb, trap heat |
| weathering | rock breaks or changes where it is |
| erosion | pieces are carried away |
| Event | Kind |
|---|---|
| ice splits a rock | mechanical |
| acid rain on limestone | chemical |
| roots lift a stone | mechanical |
| rust in a rock | chemical |
Choose and explain. Your town needs power. Make a table with wind, water and solar power. For each write one good point, one drawback and one place in Egypt where it could work (for example a windy coast, a river, a sunny desert). Then choose the one you think is best for your town and write a claim, evidence and reasoning in three sentences.