|scienceclub||Date: Monday, 20-Oct-2014, 10:30 AM | Message # 1|
|Q1: There is a famous saying in Hindi- “A sword cannot replace a needle”. Give reasons for the saying in the light of physics. |
Answer: In the physics, the pressure applied on needle gets concentrated its tip i.e. on very small area and hence it pierces the cloth easily. But to make the sword cut a surface; we have to apply much higher pressure due to large surface area of the cutting edge of the sword. Hence a sword cannot replace a needle.
Write your own answer for these questions.
1. Why don't we fall down even though Earth is revolving?
2. Why sky appears blue in colour?
3. Honey, to keep it fresh, need not bekept in refrigerator why?
4. Why tyres of vehicles are black incolour?
5. Why a bird sitting on a live wire isnot electrocuted?