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# Tag Archives: Recreation

## What do you mean by degrees of freedom?

What do you mean by degrees of freedom?

Asked Aditya Srinivasan

Answer:

Hope that your question is from kinetic theory of gases.

“The number of independent ways by which a dynamic system can move without violating any constraint imposed on it, is called degree of freedom. In other words, the degree of freedom can be defined as the minimum number of independent coordinates that can specify the position of the system completely.”

## Six degrees of freedom

**Translation**:

Moving up and down (heaving);

Moving left and right (swaying);

Moving forward and backward (surging);

**Rotation**

Tilts forward and backward (pitching);

Swivels left and right (yawing);

Pivots side to side (rolling).

## Determine unknown frequency with the help of beats

Two frequencies sounded together produce 3 beats per second.If one of the frequencies is 400 vibrations per second,the other frequency will be?

Asked Tayyab Mynir

Answer:

There are two possibilities because the beat frequency is equal to the difference in frequencies of the two sounding bodies.

So, the unknown frequency can be either 397 Hz or 403 Hz. This can be verified by lagging/ loading one of the sounding bodies.

Read more at http://en.wikipedia.org/wiki/Beat_(acoustics)

## Hot air rises up; but how?

We used to say that hot air is lighter and so it rises up. But around the hot air, there is cold air. So, how did the cold air allow the hot air to rise up.

Asked by Rashmi and Srushti of class VIII B, KV AFS Bidar.

**Answer:**

You might have seen that helium of hydrogen filled balloon rising up. Also remember the case of hot air balloons. It is the same process here too.

First of all, the air is a fluid and the molecules are free to move as there is plenty of space between the molecules. So, when the air below becomes hot and lighter, they can easily go up through the empty space in between the cold and heavier molecules. the space vacated by the hot molecules are immediately occupied by the comparatively heavier cold molecules.

## A Question from Wave motion

Two wires are kept tight between the same pair of supports. the tensions in the wires are in ratio 2:1.the radii are in ratio 3:1. and the densities are in the ratio 1:2. find the ratio of their fundamental frequencies.

Asked by Raj

## Traveling in a flight from say India to USA

If I have to travel from India to the USA, I take flight. The flight flies and keeps traveling towards USA for about say 17 hours. Why does it kepps travelling? If it flies and stays still for the hours we assume USA to be behind India time, will it land there and reach USA? If no why?

## Problems from Electricity

- The parallel plates of an air filled capacitor with area of area 1.1 x 10^8 m^2 . What must be the width of the plate be if the Capacitance is 1 Farad?
- Four capacitor each of 2microfarad are connected in such a way that total capacitance is also 2microfarad. Show what combination gives this value. Also try to illustrate the diagram.

(Fari posted these)

Answer

1.Using the formula:

and substituting , C= 1 F, A = 1.1 x 10^{8}, = 8.8 x 10^{-12},

we get , d =9.68×10^{-4} metres

## Laws of motion – The problem of descending balloon.

A balloon is descending with a constant acceleration ‘a’ less than acceleration due to gravity. The mass of the balloon, with its basket and contents, is M. What mass m, of ballast(sand bags) should be released so that the balloon will begin to accelerate upward with constant acceleration ‘a’?

Posted by Anisha Banerjee

Answer