PSLE 2009 - Science

[caroline3sg]

kohjl

thank you.

There is one question about which can travel a longer distance in a desert, lizard & snake.

My girl’s ans sounds logical but I worry the way she phrased it.

2 reasons (my own words, but her meaning:)
1) snake has no legs, there is frictional force when gliding on the (hot - not sure this word was mentioned in her ans or not) sand.

Personally, I think the longer body also plays a part on its contact on larger surface of the sand.

2) lizard uses front legs to run, hind legs to push it faster. Faster must be linked to longer distance, but don’t know / didn’t state.

[kohjl]

atutor2001:

kohjl:

b) Why?
My reason: As air is a poor conductor of heat, heat will move through the metal plate without air spaces faster than through the metal plate with air spaces. Thus, the pot on the solid metal plate with no air spaces will be heated up faster than the other pot on the metal plate with air spaces. So the water in that pot boiled faster.

From: kohjl's son

Woh! Your concept is very clear. Maybe the only other keywords are : \"while metal is a good conductor of heat\". I think it should be a 1 mark question so your answer is more than enough. A*

Oh, I did write that metal is a good conductor of heat somewhere in my exam answer. But I forgot to write it here because my mother told me to hurry up and have lunch.

From: kohjl's son

P/S: I will try to help to answer other people's questions later but I want to bathe first and then play computer. Sorry!

[atutor2001]

kohjl:

Oh, I did write that metal is a good conductor of heat somewhere in my exam answer. But I forgot to write it here because my mother told me to hurry up and have lunch.

From: kohjl's son

Looks like you are going for perfect score. Congratulation!

[hot_chocolate]

my answer for the pot/kettle question was: there is less contact between the surface of kettle b(the one with air spaces) compared to kettle a( the one without air spaces) thus, heat travels more quickly to the kettle a than b, causing the water in it to boil faster.


is my answer correct? I didn't mention that air is a good conductor of heat. :frustrated: yikes!!!

[eddie tan]

any body knows how to do the biceps and triceps Q which is in bkl A???so wats the ans for the kettle and snake Q? :? :?

[atutor2001]

caroline3sg:

kohjl

thank you.

There is one question about which can travel a longer%20distancein a desert, lizard & snake.

My girl's ans sounds logical but I worry the way she phrased it.

2 reasons (my own words, but her meaning:)
1) snake has no legs, there is frictional force when gliding on the (hot - not sure this word was mentioned in her ans or not) sand.

Personally, I think the longer body also plays a part on its contact on larger surface of the sand.

2) lizard uses front legs to run, hind legs to push it faster. Faster must be linked to longer distance, but don't know / didn't state.

This is amazing! Are they kidding by setting such question? The key words is \"longer distance\".

Are they testing adaptation for heat? I remember snake moves under the sand in the desert to shield from the hot sun. If that is the case, then it should be snake because lizard cannot move under the sand.

Hi Kohjl Jr, what is your take?

[lalala]

my boy’s ans was closed circuit too for that circuit question

[lalala]

my son is so careless. he read that the snake could travel longer than the lizard! there goes 2 marks down the drain

[acelancer]

i’m a student and i put closed circuit too…

[Sahimi]

eddie tan:

any body knows how to do the biceps and triceps Q which is in bkl A???so wats the ans for the kettle and snake Q? :? :?

My son's ans was P & R. Is it correct? :?