Q1 Two partially filled baloons one smaller than the other are connected bu a closed tube. What happens when the tube is opened. ? A1 The bigger balloon will expand. This is because stretched rubber is thinner and easier to inflate.
Q2 If camaflouge is so good in providing protection, how come green
mammals are very rare?
A. Most mammals are colour blind so it doesnot matter. Most forms of
camoflouge depend on having hides of different shades to blend in with
the surrounding.
Q3. Why does water falling from a tap thin down as it falls? A. The speed of the water increases due to gravity.
Flow rate is = speed of flow* Area of crosssection. Flow rate from the tap is constant. So water thins down.
Q4. This object is made of light wood. Basically two wings connected together to get a structure, 1-2feet across and characteristically travels through the air in a circular path. What? A. Boomerang.
Q5. Why is it more practically possible to drill a hole through the moon than
through the earth?
A. Because the earth's core is molten liquid, while the moon is frozen
solid, so it will not fill up the empty space that is drilled out.
Q6. Common experiment. Place a copper wire weighted on both sides
across an ice cube. The copper wire will fall through the ice cube,
leaving the ice cube in one piece. This however will not happen if
conducted in a freezer. Why?
A. The ice melts due to pressure, but more because the copper wire can
conduct away the heat to the environment. This is not possible in this
case.
Q7. On a cloudy day, your shadow seems to disappear even though there
is enough lighting. Why?
A. The lighting is too diffuse. So, shadows get spread over a very large
area and are very fuzzy, so they escape notice.
Q8. Space Capsules get heated on re-entry. There is another agent
besides friction which causes this, because capsules lack large wings to
provide resistance to air. What causes the heating? (hint. Think bicycle
pumps)
A. Compression of air causes heat to be generated. Same thing causes a
bicycle pump to heat up.
Q9. Why do corners of walls, parts of walls behind paintings etc, fade
less than the remainder of the wall over time? (Hint: This will not
happen in a house which is cut off from all light,both inside and
outside, especially the sun.)
A. Fading is caused by ultraviolet light which is a bleaching agent. The
mentioned areas receive less illumination and so those parts retain
colour.
Q10 Elephants drink water by sucking it up through their nose and then
putting it into their mouth. This is possible because unlike humans
their breathing and digestion passages are disjoint. Babies can indulge
in something similar. What?
A. Suckling of babies is possible because they can breathe
simultaneously while swallowing.
Q11. Why does inhalation of helium make the pitch of ones voice higher? A. Sound travels faster in helium than in air.
Q12. Emission of sulphur dioxide in a volcanic eruption causes a period of "global cooling", especially if the atmosphere is humid. Why? So2 mixes with water in the air to form droplets of H2SO4 which reflects sunlight.
Q12. How would the texture of beer in a space-ship compare to that on earth? A12.
Q12.b - This situation is hypothetical as beer is off limits for
Astronauts. Why?
A. Cannot burp.
Q13. In a very calm body of water, two bubbles which are floating coalesce. A very faint circular ripple is noticed propogating outwards. It represents some change in the configuration of the bubbles. What? A. The fusion releases energy. This causes the ripple.
Q14. Guesstimation: The volume given on the side of a beer can indicates the minimum quantity of drink it must contain. The rest of the can is usually filled with air +CO2. When some cans were put in a trough of cold water, some were found to float and some sank. Which one would you choose if you wanted more beer for your money?
A14. This owes a little to the laws of hydrostatics and a lot to consumer laws. The volume of beer that is printed on the side of a can is a legal minimum, and so beer cans are designed to accommodate a certain amount of extra liquid.
The exact amount of extra beer contained in the can depends on the brewer's quality control procedures during can filling. If the beer is accurately metered during filling, then cans need to be only slightly larger than the nominal volume of beer they contain. Where the filling process is less accurate cans must be even larger, cost more to make and transport, and may be filled with more beer for which the brewer cannot charge.
When the can is completely filled with more than the quantity of beer that is printed on the side it has a net density that is more than that of water (beer and aluminium being denser than water). When the can is filled with the minimum quantity of drink marked on the side, the rest of the can is filled with air and carbon dioxide, making the overall density less than when it is full.
Assuming that beer and air have densities of 1010 kilograms per cubic metre and 1 kilogram per cubic metre respectively, and that a nominal 440 millilitre aluminium can has a mass of 30 grams, a few rough calculations (based on the cans in my fridge) would suggest that around 8 per cent extra volume of air on top of the standard 440 millilitres of beer would be enough to make it float. This can be measured by the fill-level of the can: in this case it would be about 9 millimetres from the top.
The fact that there were more submerged than float-ing cans would confirm that brewers do overfill cans to comply with weights and measures regulations.
So, if your thirst needs plenty of quenching, or you just want more beer for your money, you should go for the cans that don't float.
Q15. When a fizzy drink is poured into a new glass, there is a considerable amount of froth formed. This does not happen if a second helping is taken in the same glass. Why?
Q16. Ice made in a traditional freezer is not very clear (even with
boiled water). What can you
do to get clear ice?
A16. This is because of air bubbles trapped inside the ice. Cool it
slowly to avoid this. (also cool warm water, so that the amount of
dissolved gas is less. )
Q17. Goggles help us see better underwater. Why?
A17. The eye is optimised for focusing light which comes from the air.
The focusing of light coming from water or some other medium will be
incorrect. Goggles ensure that the light reaching the eye is coming from
air.