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# Daily Archives: June 4, 2011

## Change in Barometric Height with position

“How would the barometric height change when a mercury barometer is taken to a mine? Give reasons to explain.”

Answer: Barometer is a device used to determine the atmospheric pressure. The atmospheric pressure is calibrated in terms of height of mercury column in the barometer.

Atmospheric pressure is the weight of air acting normally per unit area on the surface ofof earth or the point under consideration.

Inside a mine, the weight of air above the point will be more than that on the surface of earth. Therefore, the barometric height increases when taken to a mine.

## What is resultant force?

“What is resultant force?”

When a number of frces are acting simultaneously on a body, it will be producing an effect – may be keeping the body in equilibrium, or giving it an acceleration in a particular direction.

Resultant of a number of forces is defined as that single force which can replace all other forces to produce the same effect.

If the number of forces acting on the body keep it at rest or maintain uniform motion,it is said to  be in equilibrium; then the resultant is zero (since acceleration is zero).

## Mass of a charged particle !

“Can mass of a charged particle be infinite and if
yes explain how and when?????”

Answer: Please note that charge is independent of speed but mass depends on speed. So of a body of any mass is moving with gradually increasing speeds, its mass goes on increasing as per the theory of relativity (The relativistic mass $m=\frac{m_{0}}{\sqrt{1-\frac{v^{2}}{c^{2}}}}$) but the charge remains the same.

Therefore, the mass of a charged particle can be infinity.

(If any of the visitors has got a different opinion, please post them as comments to this post.)

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