Answer:
When a body moves in a circle with constant speed , it is said to be in uniform circular motion .
Explanation:
- When an object moves in a circular path , its direction changes at each point .
- This change in direction result in change of velocity (velocity is vector quantity which changes if direction of the object change) .However speed do not change (it is scalar quantity , not affected by Direction)
- The Change in velocity produce acceleration ( a = v - u)
- Hence The object always produce acceleration in uniform circular motion .So, Some force (centripetal force) is needed to keep the object in circular motion.
Answer:
Because if you use pen, your chromatography will separate also the colors of the pen and not just your sample.
Explanation:
The pencil since is carbon as simple element, is solid and is not dissolved in solvents like commonly are used in paper chromatography, it will not interrupt the separation of the compounds in your mixture, otherwise, your results will be confuse because you are not sure if the spots that you observe is due to the ink pen or due to the mixture that you want to separate.
Chromium is a fairly active metal. It does not react with water, but reacts with most acids. It combines with oxygen at room temperature to form chromium oxide (Cr 2 O 3 ). Chromium oxide forms a thin layer on the surface of the metal, protecting it from further corrosion (rusting).
