PSLE 2009 - Science

[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? :?

[MummyJamie]

Sahimi:

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

I wrote P & R too.

[caroline3sg]

atutor2001


my girl said it has diagram showing the snake on the sand.


kohjl
how about the question on farmer spraying pesticide on veg & fruit trees? Population decrease/decrease or decrease/increase?.

There is no mention that veg & fruit trees are on same plot of land. But it does mention insects/pests attack veg.

[MummyJamie]

For the snake&lizard question, I was really stumped. I skipped it & in the end just put down a rubbish answer xD


I wrote sth like the sand’s texture is rough and the sand is hot, so the snake will take a longer time to crawl on it.

I’m sure it’s wrong. Anyone knows the accurate answers?