Biology; Chemistry; Physics: Post your doubts here!

[mintchocolate4567]

hhhmmmm.....okay.thanks.

 

[SalmanPakRocks]

np

 

[mintchocolate4567]

First one: D because gamma ray is most penetrating and shorter half life as its harmful
Second one: C because of they can travel the most, aplha has a range of few centimeters while beta has range of 10 cm. And shorter half life as its harmful.

lemme check the answers,i'll get back to u in a while.there's some kinda confusion.

 

[SalmanPakRocks]

lemme check the answers,i'll get back to u in a while.there's some kinda confusion.

sure do!
and if u have confusion then i can explain it again

 

[mintchocolate4567]

sure do!
and if u have confusion then i can explain it again

well...checked the mark scheme....the answer to 1 is A....u can check it urself if u want to...it's q39-p1-j08.
as for 2....i cudn't verify its answer as the year under this question is incorrect (in my redspot topical)
thanks for the help anyways.

 

[multixamza01]

Okay ! Time to suit up people. I'm gonna ask a question regarding Physics A really technical question. So if you wanna check how much you know ... then try to answer it. Let's have 5 people guess the answer , if they're all wrong then I'll spill the answer. If anyone of them is right then they're right

So here's the question :

A glass prism , is placed on a grassy field for 3 weeks. On the 22nd day , the prism explodes and the grass catches fire. Why?

 

[DANGERBP]

U GUYZZ IM DIEIN!!! HELP MEE !!! IM APLYING FOR 4 SUBJECT A LEEL (BIO,CHEM,MATH,M1,PHYSICS) AND I CANT KEEP UP ANYMORE ! -.-
DO ANY OF YOU KNOW ANY SITE WITH NOTES WHICH I COULD USE SO TO SAVE TIME LOL ACTUALLY I HAVE NOT MUCH TIME LEFT AND SOME GOOD QUESTION TO SOLVE ON!!!
THX ! =)

 

[SalmanPakRocks]

well...checked the mark scheme....the answer to 1 is A....u can check it urself if u want to...it's q39-p1-j08.
as for 2....i cudn't verify its answer as the year under this question is incorrect (in my redspot topical)
thanks for the help anyways.

yeah my bad! Actually the reason for it being A was due to the fact that gamma rays have most penetrative powers so the rays can go through the body and enter into the brain.
P.S: I mis-interpreted the question.

 

[Alchemist4lyf]

Okay ! Time to suit up people. I'm gonna ask a question regarding Physics A really technical question. So if you wanna check how much you know ... then try to answer it. Let's have 5 people guess the answer , if they're all wrong then I'll spill the answer. If anyone of them is right then they're right

So here's the question :

A glass prism , is placed on a grassy field for 3 weeks. On the 22nd day , the prism explodes and the grass catches fire. Why?

I know that the grass catches fire because the prism has exploded, releasing heat, so 5 marks there . As for the prism, I'd say, it might have something to do with the over-heating due to too much total internal reflection of light. Or, because the prism has refracted too much light towards the grass, the grass heated up too much, and caused the prism to explode. It's explosion causing the grass to catch fire.

 

[daredevil]

Hello everyone! can anyone please give me some guidance/notes or just explain Advanced Electronics? i m not getting satisfactory guidance on that because i have been studying it for 1 whole week and still have no idea how a potentiometer or an LDR or a thermistor works or a relay or a potential divider or anny other topic of that whole section for that matter. my mocks are arriving and i am lost on that topic. please help!!

 

[multixamza01]

I know that the grass catches fire because the prism has exploded, releasing heat, so 5 marks there . As for the prism, I'd say, it might have something to do with the over-heating due to too much total internal reflection of light. Or, because the prism has refracted too much light towards the grass, the grass heated up too much, and caused the prism to explode. It's explosion causing the grass to catch fire.

Total internal reflection ONLY occurs if the angle of incidence is greater than critical angle. Only a few rays would be refracted internally. How can that set the grass on fire. The grass is in direct sunlight all day. Does it catch fire under normal conditions? And how can reflecting too much light cause the prism to explode. Think before you speak , your answers don't even make sense.

Anyone else try.

 

[Alchemist4lyf]

Total internal reflection ONLY occurs if the angle of incidence is greater than critical angle. Only a few rays would be refracted internally. How can that set the grass on fire. The grass is in direct sunlight all day. Does it catch fire under normal conditions? And how can reflecting too much light cause the prism to explode. Think before you speak , your answers don't even make sense.

Anyone else try.

Chillax mate. It's only an opinion. Alright, how's about this one... you said, that the glass prism was in the open, not sunlight or cold weather. Well, that being said, it is safe to assume that temperature variations will be present, because 22 days is a lot of time, and the weather will not be the same for that period. Now, with that assumption, we can say, that the glass had expanded unevenly. That has caused it to break and explode. This explosion, causes the grass to catch fire.
Again, this is only an opinion. Might seem stupid to you, but you can try being nicer with your replies next time round. Condescension is implied in your tone.

 

[multixamza01]

Chillax mate. It's only an opinion. Alright, how's about this one... you said, that the glass prism was in the open, not sunlight or cold weather. Well, that being said, it is safe to assume that temperature variations will be present, because 22 days is a lot of time, and the weather will not be the same for that period. Now, with that assumption, we can say, that the glass had expanded unevenly. That has caused it to break and explode. This explosion, causes the grass to catch fire.
Again, this is only an opinion. Might seem stupid to you, but you can try being nicer with your replies next time round. Condescension is implied in your tone.

. Wrong again. It actually is a bit silly . Expansion is very minor in solids . It wont be like the prism becomes a skyscraper. Okay , say your right. The prism become hot and expanded. Then when the temp dropped it would crack due to compression. So it breaks. Even so , it's just glass. How can glass breaking set fire to the grass?

 

[Alchemist4lyf]

Alright, this time, thank you for the nice reply ^_^. But, as you can see, I'm just guessing. I may be wrong, but at least I'm trying. This time, I'm going to sit it out. See what the others have to say.

 

[hassan100]

Chillax mate. It's only an opinion. Alright, how's about this one... you said, that the glass prism was in the open, not sunlight or cold weather. Well, that being said, it is safe to assume that temperature variations will be present, because 22 days is a lot of time, and the weather will not be the same for that period. Now, with that assumption, we can say, that the glass had expanded unevenly. That has caused it to break and explode. This explosion, causes the grass to catch fire.
Again, this is only an opinion. Might seem stupid to you, but you can try being nicer with your replies next time round. Condescension is implied in your tone.

Seriously man u CHillax, u guys are fighting such a senseless problem. Get a life man , no body is gonna ask you about wat would happen if u put prism (huh! ) in sunlight in your exams
So chill !!

 

[DANGERBP]

. Wrong again. It actually is a bit silly . Expansion is very minor in solids . It wont be like the prism becomes a skyscraper. Okay , say your right. The prism become hot and expanded. Then when the temp dropped it would crack due to compression. So it breaks. Even so , it's just glass. How can glass breaking set fire to the grass?

hahaha ok ! lol u seem so clever man ! =)
lol say it already ! !

 

[multixamza01]

hahaha ok ! lol u seem so clever man ! =)
lol say it already ! !

Well , i guess i have to , since everyone is all but prepared.
It's because of what you call ''Greenhouse Effect''. The light rays have to lose a certain amount of energy to pass into the glass prism. Once inside , they have to lose the same amount of energy to pass out.But they don't hve the required amount of energy , hence they are trapped in the prism. When billions of these infre red rays get trapped in the prism , it increases the temperature and pressure inside the prism. With time , the prism explodes like a bomb and the heat energy is transferred to the surrounding grass. The grass heatd up rapidly due to the sudden absorption of heat. The immense heat causes the grass to catch fire.

Seriously man u CHillax, u guys are fighting such a senseless problem. Get a life man , no body is gonna ask you about wat would happen if u put prism (huh! ) in sunlight in your exams
So chill !!

Is that such a senseless concept? You should think twice before you speak pal.

 

[GetSomeLife]

Wat vol of ammonia can b dissolved in 1 cm3 of water? I think it was around 700 cm3 bt i wanna kno d xact answer...TEACHER ASKED TO

 

[SalmanPakRocks]

Please avoid arguing here.

 

[Saad12345]

Hey could anyone suggest which books are best for O level physics and chemistry? or if anyone could post useful, compiled and complete notes on them i would be grateful.