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# Tag Archives: altitude

## Is the acceleration due to gravity different in south pole and north pole

“Is the acceleration due to gravity different in south pole and north pole?”

As per theory, acceleration due to gravity changes with altitude, depth and latitude.

If we consider that the variation of g with latitude is caused by rotation of earth only, then the value of g will be same for both north pole and south pole.

But, the change in the value of acceleration due to gravity with latitude is caused by the shape of earth too. So it depends your distance from the centre of earth when you are at north pole or south pole.

For calculations the polar radius is taken same at North as well as south pole. So, value of g can be taken the same for both poles.

## Relative position of a helicopter

If a helicopter takes off from a point on earth.(at certain altitude) and its still at that point in air.After certain time interval the observer whose position was same as that of helicopter’s take off point will see the helicopter right above him.
The question arises is that how it is possible if earth is rotating hence the observer is also, but the helicopter is in air.How is it possible?
Thanks…

## Potential Difference – misconception

What actually it means when we say “potential difference across..” ? Does it indicate that the somehow the energy level of electrons across it is less than on the other side or is it just the amount of energy consumption across it. If latter is true then in AC we’ve voltages which dont algebraically add up together to give the applied voltage . reason stated is the phase difference. How can there be phases in something scalar like energy consumption ? (Posted by Thushar)

Answer: As per definition, “Potential difference is defined as the work done per unit charge in carrying a positive test charge between two points against the electric field.”

Just like water flows from a high altitude to low altitude, “current” flows from high positive potential to low positive potential. (And electrons flow in the reverse direction. Though electrons are the actually movable materials contained in a conductor, the direction of current was conventionally defined as the direction of motion of positive charges)

So, when there is a difference in potential the electrons will flow from lower “positive potential” (where the negative potential is high) to higher positive potential.

Phase refers to the angle of rotation corresponding to the present value of emf or current. One complete circle (or rotation) corresponds to 2(pi) phase. There is a difference between current and voltage refers to this.

In describing AC, we can imagine that the current and voltage in wave form is obtained by the projection of  rotating vectors, I0 and E0. The difference in angle between these which represents the waveform obtained for E and I correctly is known as the phase difference.

(I feel that this won’t suffice. Please as more questions to clarify your point; preferable as comments to the same post)

## Why don’t we get a shock when we step out of house?

the top of the atmosphere is at about 400kv with respect to surface of the earth,corresponding to an electric field that decreases with altitude. near surface of the earth the field is about 100v/m. why then do we not get an electric shock as we step out of our house into open?

## Pendulum on Mount Everest !

If you set a pendulum atop Mt. Everest, would the period be less than, greater than or equal to the period you would get in the lab?  Explain.

Ans:

As you know, the acceleration due to gravity decreases as we go upwards from surface of earth.

The time period of a simple pendulum is given by

Where l is the length of the pendulum, and g is the acceleration due to gravity.

From the equation, we can conclude that, the Time period of the pendulum increases (i.e. it goes slower)  if the pendulum is set up on top of Mount Everest.

For Creative and Critical Thinkers

Here we have not considered the change in temperature between the laboratory conditions and the temperature on top of Mount Everest which is very low. A decrease in temperature would decrease the length of the pendulum (Unless it is made up of such a substance which does not change its length with change in  temperature) and will also decrease the time period of the pendulum, making it move faster.

My first answer is correct only if the laboratory conditions are the same as on top of Mt. Everest or vice versa, except for the difference in altitude (height)

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