108-1 The Way Science Works : Mid-term Exam

10 points each question

1. When dried and harden, cement is rock-like, so it resist both compression and tension.

2. Arch structure has every internal part compressed when under pressure from above.

3. Steel cable bridge only works when there are suitable anchor points on both sides of the river banks.

4. The name Sodium Chloride means when the compound is formed, Sodium loss electron and Chlorine gain electron.

5. Alum is used for cleaning water in large scale, the precipitate are non-toxic , so after collected and dried they can just fill the land.

6. Whether a dusk particle will sink is all about their equally received kinetic energy. The more massive one is jiggling less, so fluctuation can not undone the pulling of gravity so they go down.

7. The purpose of planting trees and keep environment natural in the water collecting area is to make sure the water being very clean and Methane (CH4) free, so that reduce the possibility of generating cancer causing CHCl3 during necessary chlorination procedure.

8. Centrifugal (high-speed rotating) filter is to make the released water clean and clear.

9. Releasing untreated domestic sewage will make river oxygen rich, help bacteria grow to release poisonous substance to damage ecosystem.

10. The reason of sending electricity in super high voltage is to overcome the limit of transmission distance.