Things I learnt beyond textbooks! 

1) Acids and Bases 

Acids

• Tastes sour(E.g. Lemon)
• Changes blue litmus paper to red colour

Basics

• Feels slippery(E.g. Soap water)
• Tastes bitter 
• Changes red litmus paper to blue colour 

The table below shows the pH level scale from 0-14. 

	pH
Acids	0(Lead battery acid)
	1
	2(Gastric acid)
	3(:emon)
	4(Tomato juice)
	5(Coffee)
	6(Urine)
Neutral	7(water)
Bases	8(Seawater)
	9(Household ammonia)
	10
	11
	12
	13
	14

2) Water Pressure

The weight of the water on top creates pressure on the water underneath, which makes water spurt out rapidly when there is an opening. The pressure is proportional to the depth of the water above the opening thus if the hole is placed at the top there would be less water pressure. As the water level drops, there is less pressure, so the flow through the opening slows down.

 

3) How a fan works.

An electric fan is an electric motor with some fan bladse attached to its rotating shaft. As the fan blades rotate, each blade is inclined a bit, and as the inclined plane of the blade moves through the air, it forces the air ahead of it forward. Each blade does this on a continuous basis, and the result is a moving air stream. The fan takes air from the area behind itself and blows it out the front. The fan generates a movement of air, causeing the warm, less dense air to rise, and the cool, dense air to descend, thus creating a feeling of coolness in the air.