IIT JEE , AIEEE Forum - Physics , General

smartboy198062

these r the facts extracted from the world famous text book,

Resnick and Halliday

they r most likely to be used in assertion and reasoning

spearhead121

i need to get spectacles... :|

where are the facts?

destinationIIT09

same here SPEARHEAD121

so it was not my eye prob

SCIENTIST135

I THINK THE FACT IS THAT YOU SHOULD READ Resnick and Halliday BOOK !!!!

smartboy198062

On April, 1974, John Massis of Belgium managed to move 2 passenger cars belonging to the new york?s railways.

He did so by clamping his teeth

Down on a bit of rope that was attached to the cars and then leaning backwards. The cars together weighed more than 80 tons. How??

The cars required a low acceleration and a force of about 2000N this could be supplied by a good middle weight-lifter quite easily.

Cats who enjoy sleeping on window sills, r often kept in apartment buildings.

When a cat accidentally falls, the extent of injury decreases with the height of the fall if the fall is of more than 6 floors. How ??

The reason is explained thus: a cat must fall about 6 floors to reach the terminal speed. Until this it accelerates. Its body is an accelerometer, not a speedometer, so the cat sensing acceleration keeps its feet under the body and head tucked in making it to reach terminal velocity in lesser time, after reaching terminal velocity it senses no acceleration and stretches out increasing surface drag. So velocity decreases and the landing is safer.

Ps: will post many more later

smartboy198062

or maybe as suggested read the book urself

smartboy198062

A normal human being taking a leap maps a path matching a parabola. Skilled ballerinas are able to glide across a stage with head and torso nearly horizontal, giving the appearance of floating across the stage. How ??

The center of mass of the ballerina still moves in a parabola. However the ballerina orients her head to move in a straight path.

A pine board requires about 3 times the strength and energy required to break a concrete block. However it is easier to break a board. Why??

Because the board is much lighter, hence in a given collision it acquires much more velocity for the given fist speed than the far heavier concrete block.

smartboy198062

The giant hornet Vespa Mandarina Japonica preys on Japanese bees. However, if one of the hornets attempts to invade the bee hive, several hundreds of the bees quickly form a compact ball around the hornet to stop it. After 20 minutes the hornet is dead, though the bees do not sting, bite, crush or suffocate it. How ??

This is because the bee ball generates sufficient heat energy to kill the hornet given their large volume-surface ratio and heat the hornet to death.

The force exerted by water on the body of a descending diver increases noticeably, even for a relatively shallow descent to the bottom of a swimming pool. Amateur divers often face the great risk due to this water pressure. How ??

The fact is that below the water surface the lung air pressure is equilibrated with that of the water at that depth. If the diver does not gradually exhale while ascending to the surface, he will arrive at the surface with surplus air pressure which may rupture his lungs and cause cardiac arrest due to air embolism. If the diver follows instructions and gradually exhales as he ascends, he allows the pressure in his lungs to equalize with the external pressure and then there is no danger.

smartboy198062

When a beetle moves along the sand within a few centimeters of a sand scorpion, the scorpion immediately turns to attack the beetle without aid of sight and sound. How??

It does so by timing the difference between fast longitudinal and slow transversal pulses created by the beetle?s movement on sand.

When a container of cold champagne, soda pop, or any other carbonated drink is opened, a slight fog forms around the opening and some liquid sprays outwards. Why ??

The gas inside the carbonated drink undergoes adiabatic expansion when the can is opened. This causes cooling and condensation and hence the fog is formed.

All physical processes show ideally no difference with regard to time that is it does not matter whether time decreases or increases. Which law differentiates this for a process?

The second law of thermodynamics. Entropy always increases with time and never the reverse.

smartboy198062

Multiple electric charges are seen over some volcano craters. Why? As this is not a thunderstorm.

It happens because liquid water within the volcano is suddenly converted to steam and is spewed as ash causing separation of +ve and ?ve charges which produce pockets of +ve and ?ve charge causing lightning display.

The pride of Germany and a wonder of its time the zeppelin hunclenberg was the largest flying machine ever built. Kept aloft by 16 cells of highly inflammable hydrogen gas it made many trans-Atlantic trios without incident. However it burst into flames on May 6^th 1937, during its launching.

Why ??

That was a rainy day and the fabric of the ship got wet. As the conductivity of rainwater is different, potential developed in rain water is also different. Because of potential difference charge flowed along the wet fabric causing ignition of hydrogen in the process and brought the ship down. If the sealant on the outer fabric of the ship had been of less reactivity the disaster wouldn?t have occurred.

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