physics question

anpanman SG

there are 4 similar cans containing the same volume of water initially at 80 deg cel. after 5 mins, whcih can will contain the coolest water

A the dull black can

B polished silver can

C dull black can with cover

D polished silver with cover

My answer is A, however answer given is B. i thought that's impossible since the silver can can reflect radiation from the hot water back into the can and thus retain heat?

the unit of specific latent heat is J/g right?

if yes, then tys should have given the wrong answer

thank you!

Forbiddensinner SG

there are 4 similar cans containing the same volume of water initially at 80 deg cel. after 5 mins, whcih can will contain the coolest water

A the dull black can

B polished silver can

C dull black can with cover

D polished silver with cover

My answer is A, however answer given is B. i thought that's impossible since the silver can can reflect radiation from the hot water back into the can and thus retain heat?

the unit of specific latent heat is J/g right?

if yes, then tys should have given the wrong answer

thank you!

A should contain the coolest alright.

Unit of specific latent heat is J/Kg.

dkcx SG

B is not wrong i would say.

Because a shiny surface can reflect heat, it also losses heat very quickly.

A black can will retain the heat and this will continue to keep the water warm since the can will heat the water back.

MasterMoogle SG

B is not wrong i would say.

Because a shiny surface can reflect heat, it also losses heat very quickly.

A black can will retain the heat and this will continue to keep the water warm since the can will heat the water back.

dun blame shi fu, he half baked der for physics

ƒlame SG

Since the question did not state where the cans are placed, I am assuming it's black. Why ?

Black absorbs heat the fastest as it is a VERY GOOD conductor of heat in any heated places but Black also releases heat energy to the surroundings the fastest when it is placed in any cold places.

Silver should not have been the coldest as silver colour is an insulator of heat and does not allow heat to escape quickly.

Not sure if I'm correct though.

dkcx SG

Easiest is juz go do expt lo. 5 mins only. Very fast can get results

I hate physics :p

ƒlame SG

My answer is Correct right ? HAHAH i rock at physics !

dkcx SG

My answer is Correct right ? HAHAH i rock at physics !

Izzit? I dunno cos my physics sucks as with most chemistry students but to be fair, physics students mostly sucks at chemistry as well.

* This is for higher level physics and chemistry students not O's A's level.

ƒlame SG

Izzit? I dunno cos my physics sucks as with most chemistry students but to be fair, physics students mostly sucks at chemistry as well.

* This is for higher level physics and chemistry students not O's A's level.

Question is on Radiation, Conduction and Convection. Lol....

dkcx SG

Question is on Radiation, Conduction and Convection. Lol....

Alot of chemistry undergrad cannot handle physics regardless of level. It seems the more chemistry we study, the worse our physics become. Thats similar to some of my physics major friends and we often comment how each other study all the crap that cannot be understood :p

ƒlame SG

hahah nice... what course you are in now ?

dkcx SG

hahah nice... what course you are in now ?

Isn't it obvious i'm a chemistry undergrad? :p