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# Tag Archives: person

## Can a body be said to be at rest as well as in motion at the same time?

“Can a body be said to be at rest as well as in motion at the same time?”

This question was asked by Anmol.

Motion and rest are relative concepts. There is no absolute rest. We can define the state of rest or motion only with respect to another object or a point in space taken as reference.

For example, a person inside a train considers himself to be at rest with respect to the fellow passengers or the walls of the train. But when he looks outside, he finds himself to be in motion with respect to the trees outside.

Hope the idea is clear.

## A Question From Relativity

“my question is on relativity.Let us say two persons,one is standing still and other is moving with uniform velocity in a straight line(in +ve x direction),both are carrying  a clock synchronized previously.For the moving person he is at rest and the other guy is moving away from him in the opposite direction(negative x direction).Both of them feel that clock of the other guy is moving slowly.let us say the moving guy never stops and he calls the other in telephone at some point of time and asks the
time in his clock.But he will find that clock with him,is actually faster.how can that happen?”

Please note that the theory of relativity can  be applied only for velocities compared to that of light in vacuum (3 lakh km/s). The situation will be very much different when we travel at such velocities. So far we are able to accelerate only subatomic particles to this speeds (LHC).

## The person in a Portrait always looks at me?!

“when we look continuously into the eyes of a person in a photo frame and change our position then the person appears to follow us.why is it so?”

Ans: Because the portrait is inanimate and is drawn in such a way that it is looking at the spectator. So, it will seem to be looking at you when you look at it. But this will not happen in the case of a statue.

## When does a person wear a specs with both concave and convex lens?

When does a person wear a specs with both concave and convex lens?
:

A person uses bifocal lenses, while suffering from presbiopia.

Bifocals are eyeglasses with two distinct optical powers. Bifocals are most commonly prescribed to people with presbyopia who also require a correction for myopia, hyperopia, and/or astigmatism.

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