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1. ### help! 12 principles of Green Chemistry

...近年green chem. 科研上一項成功的例子, 它可以應用於塑膠工廠 另外我補充多項 principles of Green Chemistry, (個網址沒寫出黎) In past, percentage...

分類：科學及數學 > 化學 2008年07月18日

2. ### Archimedes’ Principle

(b) Upthrust on box = 450 kN Hence, weight of water displaced = 450 kN Mass of water dispalced = 450000/g kg = 4.587 x 10^4 kg Volume of water dispalced = 4.587 x 10^4/1025 m^3 = 44.75 m^3 Thus, h = 44.75/(pi x 2.5^2) m = 2.279 m (c) Pressure at half...

3. ### Archimedes’ Principle

1. (a)(i) weight of person = 50g N where g is the acceleration due to gravity (ii) Upthrust = 50g N (iii) Weight of water displaced = upthrust = 50g N 2. Upthrust = 1.2 x 0.05g N = 0.06g N 3. (a) Weight = 7800 x (0.5^3)g N = 975g...

4. ### pigeonhole principle

if no three consecutive players have the sum of their numbers at least 20, then the maximum value is 19 Generally speaking, for a circular arrangement, the total no of count of three consecutive players is 12 the maximum total values is 12*19...

5. ### Archimede principle

Volume of air displaced by the balloon = 2000 m^3 Upthrust on the balloon = weight of air displaced = 2000 x 1.25g N = 25000 N where g is the acceleration due to gravity, taken to be 10 m/s^2 Weight of hot air inside balloon = 2000 x 0.95g N...

6. ### Archimede principle

= Its weight 3500 kg - Buoyancy (1000 kg) = 2500 kg 2013-11-07 23:15:21 補充： Since the metal box is cubical and has side length 1m. Its volume is 1 m³, when it is completely immersed in water, it displaced 1m³ water and experience...

7. ### Archimede principle

(a) Let L be the length of rod immersed in water Upthrust = weight of water displaced = L.A.(1000)g where A is the cross-sectional area of rod and g is the acceleration due to gravity Since weight of rod = (0.5A).(920g) thus, 0...

8. ### what is a bridge Principle ?

A bridge is a structure built to span a gorge, valley, road, railroad track, river, body of water, or any other physical obstacle. Designs may be built higher than otherwise needed in order to allow other traffic (particularly ship traffic) beneath. The purpose of a bridge...

分類：科學及數學 > 工程學 2006年12月11日

9. ### Effective management principle

What is the 5 effective management?? 1. Division of labour 2.Unity of command...

10. ### jet engine principle

The compressed air inside the engine is heated and expands rapidly. The pressure of the hot gas increases. It is directed by the engine chamber to the exhaust opening at the rear of the engine. In fact, a jet engine...