A set is open iff for every point , there exists a such that the neighborhood surrounding is completely contained within (is a subset of) . A point is a limit point of a set iff given any , all neighborhoods intersect the...

# Category - Physics, Math

Interesting Physics and Math Stuff

If a woman is standing in an elevator, she feels a force of gravity pushing her against the floor. As the elevator accelerates upwards, this force increases. She still feels as if a ‘gravitational’ force has increased...

Centrifugal force is observed by the rotating bucket of water – pulling it towards the center. The bucket of water is in a noninertial frame ,what we (in our own inertial frame) observe is the centripetal...

Is 20 C twice as hot as 10 C? No – because the centigrade scale does not start at 0.For e.g.- if we used a meter scale that started at 1.0 meters, what can you say about comparing 1.1 to 1.2? Can you say that 1.2 is TWICE...

The original problem Three doors, a prize behind only one door (say, a new car). Other two doors are each hiding a goat. Contestant has to pick a door – and hope that she wins the car. At just this stage, the chance of...

Counting Elements versus Counting Intervals The interval [0,1) for example is uncountable, but we are not counting ELEMENTS of an interval, we are counting INTERVALS. [0,1] is one interval, [0,1/3] is another and so...

How often have you stared at a math (or physics) problem, unsure of where to begin? Most math books are unusually pedantic and dull – all in an attempt to be more ‘rigorous’. Screw rigor, I say. Students are...

The short answer is ‘No’. If you think about what the zero-point energy represents, it is the lowest POSSIBLE energy state of a system. For us to extract any energy out of this system would leave it in an even lower energy...

Galilean Transformation – v’ = v +- V – cannot be applied to light If (x1 , t1) and (x2,t2) are two events in K, and (x1’,t1’) and (x2’,t2’) are their co-ordinates in K’, then (x2 –x1) / (t2 –...

A Logical Paradox – The British Air Force Bombing Paradox The British Airforce announces that it will bomb the city sometime during this week; but at an unpredictable date. Why is this paradoxical. Suppose, they announce this...