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Almost any gas will work, as long as it doesn't react with the balloon material. Air is the cheapest, Hydrogen is the lightest if you want it to float, but since the Hindenberg disaster it is considered a dangerous substance so we usually use Helium. Other gases have different physical characteristics, like some are fairly heavy compared to the air around us. Some change the rubber or mylar or whatever the balloon is made of into something unexpected. Fun with chemistry!
Read more: http://wiki.answers.com/Q/What_gas_is_used_for_filling_balloons#ixzz19PTkd0od |
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To secure admission in Bansal Classes you need to have certain minimum %age (refer course descriptions) as an aggregate in PCM as eligibility to give an entrance exam. http://www.bansaliitjee.com/oltpublish/bansal/cms.do?view=admission http://www.bansaliitjee.com/oltpublish/bansal/cms.do?view=courses
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http://www.google.co.in/#hl=en&safe=off&biw=1280&bih=570&q=%2B977&aq=f&aqi=&aql=&oq=&gs_rfai=&fp=9af714dd4ddc1fb2 at least tell what u're talking about like some mob no. etc
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If the cycle is being propelled forwards then the rear wheel is pushing rearwards quite hard at the road. It is prevented from slipping on the road by the opposing friction force which acts in a forward direction on the rear wheel at the road surface.
The front wheel is essentially nearly always running free (so long as the brakes are not being applied). However there is a small force required to turn the front wheel against the torque produced by air resistance on the spokes and bearing friction. Again this is suppled by friction at the road surface. This time the friction force has to keep the front wheel turning forwards so down at the road surface it acts backwards on the wheel.
Fundamentally this is all based on action and reaction being equal and opposite. If you want to move forwards (by any means - walking, cycling, swimming, flying) you have to push backwards and your backward push has to meet with resistance which friction can very effectively supply.
source : http://in.answers.yahoo.com/question/index?qid=20100712060726AAjfxim
a bit lazy nowadays that's why i'm copying ans from the net .... hope this helps
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In bicycle, pedalling is done on rear wheel. This means that we try to rotate the rear wheel to move forward. The rear wheel pushes the ground backwards and gets the forward frictional force which pushes the bicycle forward.
The front wheel is being pushed forward (through the connecting rod between the rear and front wheels) which results in the backward frictional force on its tire which rotate it in the same direction as the rear wheel.
The static frictional force which acts on both the wheels is a friendly force that helps the bicycle move without loss of energy. Energy loss is due to rolling friction which is backwards on both the wheels.
Conclusion:
Backward static frictional force (opposite to the direction of motion) on the front wheel and forward static frictional force (in the direction of motion) on the rear wheel. Rolling frictional force is backwards on both the wheels. There will be no kinetic friction on the bicycle unless it skids due to sudden application of brakes or due to muddy and slippery road.
As the bicycle tires are moving in the anticlockwise direction, bicycle is moving from right to left. In this case,
( i )
Static frictional force acts on the front wheel from left to right (opposite to the motion of the bicycle) and on the rear wheel from right to left (in the direction of motion of the bicycle). This is a friendly force which helps bicycle move forward and no work is done against it.
(ii)
Rolling friction acts on both the wheels from left to right (opposite to the motion of the bicycle) and work is done to overcome it.
(iii)
Kinetic friction is absent as long as the bicycle does not skid. It is from left to right (opposite to the motion of the bicycle) in the case of skidding. If kinetic frictions acts, work will have to be done against it which will result in loss of kinetic energy and hence speed of the bicycle.
(iv)
There is also the frictional force in the bearings of the wheels which will need more force to accelerate the bicycle and more energy to maintain the speed if the bearings are not sufficiently lubricated. source : http://in.answers.yahoo.com/question/index?qid=20100506132221AAWpMIu
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first .. stop asking such questions stop wasting ur time on the net searching for its answer 6 months is a hell lot of time.......... get ur stuff together .................. start studying from the first chap u feel u know a bit ... it will give u a good start , then u have to keep urself together and just go on with the flow ........
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http://www.goiit.com/posts/list/community-shelf-is-exam-stress-killing-you-fight-it-51848.htm http://www.goiit.com/posts/list/community-shelf-analysis-of-i-i-t-j-e-e-45345.htm don't worry buddy ........... u've got "6 MONTHS "!!!!!! its a lot of time ........ some of my friends started getting serious even later and still made it (they were not geniuses ...... but they didn't freak out either)............... freaking out is the best way to fail. u got to get serious .. get regular ......... get some help from your friends .... keep yourself calm
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see these http://www.purplemath.com/modules/binomial.htm http://en.wikipedia.org/wiki/Binomial_theorem
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Isomers are molecules that have the same chemical formula, but a different arrangement of atoms. They are compounds, and in some cases the types of bonds and chemical properties are similar or identical, but this is not necessarily true. Propanol, C3H8O, has two isomers: propan-1-ol and propan-2-ol. Methoxyethane is also an isomer of C3H8O, but methoxyethane has very different properties from the propanols, which are very similar to each other.
Allotropes are not compounds, but rather different forms of the same pure chemical element. Allotropes refer to multiple bonding structures in the same phase of matter, and not the fact that the bonding structure is different between, say, a solid and a liquid composed of the same element. Diamond and graphite are a good example of allotropes; both are pure carbon.
Polymorphism describes variations in the crystal structure of a material. It is very similar to allotrophy, except that it refers to compounds instead of elements.
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on orkut the seniors say we will most probably get hp laptop , but if we pay more we might get the apple ones .
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me too joining manipal cs , 12th block
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Vriti Edustore
