Why i can't flying in the sky?(5 point)

Due to Newton Third Law of motion, a force with opposition direction exists when an object is being forced.

When the bird's wing moving up and down, there exists a force downward and the air push the bird upward(also due to the pressure difference). The condition is that the surface area of the wing should be large so as to gain a larger pressure.

Pressure = Force / Area ----> Force = (Pressure) (Area)

When area increases, the force increases.
As the surface area of your hand is not large enough, you can not fly.

1. There are more food on the ground.
2. It is very tired to fly, it is waste of energy.
3. If you can fly, there is a pair of wings. They must be very big and disturb you life.
4. If you can fly, you will ask " Why can I fly ? "

I want to fly too.

因為人既重量比雀仔高好多,而且雀仔既翼好大塊,當向下擺動時,就可以將大量空氣推去下面,空氣就會比番反作用力比隻雀仔,令到佢向你移動.
由於雀仔既體重連1KG都唔夠,佢既重量就細過10N,只要雀用大過或者等於10N既下向下擺動對翼,就可以向上飛.
相反人類,由於體重大部份在50KG以上,重量就大過500N,須要製造大於500N(相等於舉起自己)向下既力先可以,向上飛,就算真係比到500N向下既力,由於人類冇翼,當你一用力既時侯,空氣已經散開左,所以你跟本比唔出500N向下既力,所以,人類係好難飛到.