力學有什麼重要點??力學好難呀...溫時很容易混淆d概念...力學有什麼重要點??
5該,,,teach me..
2007-03-21 09:41:36 · 2 個解答 · 發問者 ka yan 1 in 科學 ➔ 其他:科學
最重要在於,畫圖講故事。
做每一題都要認真畫圖:
eg: a->
0m/s 20m/s
o---> o--->
{------50m------}
4s
free body diagram都唔好懶,要認真諗清楚。
唔好死背公式,要真係明。
溫的重點在於:
3(4)基公運動學公式。
newton's second law (note:係net force=ma,唔係F=ma!)
energy--->net forec x distance
--->p.e=mgh
--->k.e=1/2mv^2
power=energy/time taken
momentum=mv
momentum change=mv-mu
impulssive force=ma
=m(v-u)/t
=momentum change/time
conservation of momentum
conservation of energy
phy唔係一科記野ge科,要考更好一定要明,所有公式都只係工具。唔明一定要問!
希望幫到你^^
2007-03-21 15:11:37 · answer #1 · answered by chan 2 · 0⤊ 0⤋
There are only three important equations:
1. impulse = change of momentum
2. work done = change of kinetic energy
3. force = mass x acceleration
togethr with the two conservation laws (conservation of energy and conservation of momentum), you could solve over 90% of the calculation problems.
2007-03-21 09:51:12 · answer #2 · answered by 天同 7 · 0⤊ 0⤋