PSLE 2012 - Science

[charsen]

Hi

A stationary object has friction,known as static friction.Everybody knows that earth is moving.Therefore,we have friction with the surface we are on so that we do not slip down to the ground.This has been stated in the PSLE revision guide.
cheers

[Rational_Parent]

charsen:

Hi

A stationary object has friction,known as static friction.Everybody knows that earth is moving.Therefore,we have friction with the surface we are on so that we do not slip down to the ground.This has been stated in the PSLE revision guide.
cheers

Charsen, please paste the portion of the PSLE revision guide you are referring to for KSP and interested parties to appreciate, just like Sun_2010 did when we were referred to a document from MIT for our understanding on friction etc.

And here's my two cents worth.......

Everyone should know that gravity keeps all things grounded on earth. Therefore, you do not fall off because of gravity, and unless you drag your feet (i.e. create lateral motion) you will feel and experience friction, and normal force being the weight that you want to exert against the ground you are sliding your feet on.

In other words, there is no frictional force in play until you generate lateral motion with your feet. The amount of frictional force depends on the foot wear you are wearing, and the type of surface your feet is on, and the normal force exerted. Your feet may move restrictively (i.e. kinetic friction at play) or stay put (i.e. normal force unable to overcome static friction).

IMHO, this question seeks to examine the understanding and knowledge of students not just on friction per se but also on the contributing factors (e.g. gravity, normal force, motion, etc) to friction. Science is too diversified a subject and MOE can only set a finite number of questions for students to complete in a fixed time frame. I also do not think MOE wanted to sieve the men from the boys so to speak but it will likely turn out this way if this forum is anything to go by.

Unless there is compelling reasons for me to think otherwise, I am leaning towards what Sun_2010 had convincingly contributed, that there is no friction force when an object is resting on a flat platform.

[verykiasumummy]

oh so many similar as well as different opinions regarding the friction question. so as to say, it should be most likely "ambiguous in the question setting and therefore people made different assumptions". m i right to say that??


i really wonder how the p6 science in another 10yrs time will look like… Pure physics and Pure chemistry?? goodness…

despite all that has been said, no one is 100% sure of the answer, whether it is too much to ask of a p6 or whether they think too much… i guess only the moe knows it themselves… lets move on with it to ensure all other questions are not as ambiguous as this is…

[verykiasumummy]

Bookwrappers:

verykiasumummy:

[quote=\"kwcllf\"]
No wonder you call yourself \"verykiasumummy\"

sorry ya... it is 23 sci guides.... oh my god.... :yikes: :yikes: :yikes:

Wow ksmummy, how to get 22 sci guides in the first plc? Wun u forget n buy 2 of the same?[/quote]hi bookwrappers, i read every single bit of the guide so it is unlikely i cannot remember the content and buy another similar one.... i dun buy them to be displayed nicely in the bookshelf only...

[rains]

Yapyap:

My bother, whose sc teacher saw the answers, says that she said the the answer to the frog/tadpole question is that the tadpoles don't compete with the frogs for food, and if predators eat the frog, they cannot eat the tadpoles.

Eh, you want to bluff also cannot bluff until like that lah. Psle marking hasn't started and the teacher got to see the answers ah? I think even principals also cannot see yet leh.

And tadpoles and frogs eat different types of food. How can competition for food be possible?

Tadpoles eat insects and frogs eat algae or plants ah?

[sammifan]

rains:

Yapyap:

My bother, whose sc teacher saw the answers, says that she said the the answer to the frog/tadpole question is that the tadpoles don't compete with the frogs for food, and if predators eat the frog, they cannot eat the tadpoles.

Eh, you want to bluff also cannot bluff until like that lah. Psle marking hasn't started and the teacher got to see the answers ah? I think even principals also cannot see yet leh.

And tadpoles and frogs eat different types of food. How can competition for food be possible?

Tadpoles eat insects and frogs eat algae or plants ah?

Hello how u know ah? Ppl who wrote that are not bluffing. They can compete for food ok?!?!? U think u marker ah? Pls keep words to urself . ANYWAY, PSLE WAS OVER LIKE A WK AGO SO WHATS THERE TO DISCUSS

[rains]

sammifan:

rains:

[quote=\"Yapyap\"]My bother, whose sc teacher saw the answers, says that she said the the answer to the frog/tadpole question is that the tadpoles don't compete with the frogs for food, and if predators eat the frog, they cannot eat the tadpoles.

Eh, you want to bluff also cannot bluff until like that lah. Psle marking hasn't started and the teacher got to see the answers ah? I think even principals also cannot see yet leh.

And tadpoles and frogs eat different types of food. How can competition for food be possible?

Tadpoles eat insects and frogs eat algae or plants ah?

Hello how u know ah? Ppl who wrote that are not bluffing. They can compete for food ok?!?!? U think u marker ah? Pls keep words to urself . ANYWAY, PSLE WAS OVER LIKE A WK AGO SO WHATS THERE TO DISCUSS[/quote]Aiya, so incidental that I happen to be the marker lor - that's how I know he's bluffing! Ya lor. Psle over one week already. What's there to discuss? Then you still come and discuss for what?

[Nebbermind]

rains:

Aiya, so incidental that I happen to be the marker lor - that's how I know he's bluffing! Ya lor. Psle over one week already. What's there to discuss? Then you still come and discuss for what?

:rotflmao:
Good one there!

[atutor2001]

My teacher told me that the answer for the frog question must be, and can only be answered in the following way (just kidding):


They live in different habitats to increase the chance of survival of its kind. During a dry spell, when all water bodies have dried up, the adult frogs burrow underground and continue to survive. The adult lay eggs in shallow ponds because there is less predators and this will increase the chance of survival of their young.

[AWSP]

MeKiasuLeh:

Science is too diversified a subject and MOE can only set a finite number of questions for students to complete in a fixed time frame. I also do not think MOE wanted to sieve the men from the boys so to speak but it will likely turn out this way if this forum is anything to go by.

Do we really have so much faith that there could be no error with MOE?
Have anyone ever wondered if there could be anything wrong with the PSLE T-score? A magic formula that no one knows but can only guessed at the working? Is it based on a normal distribution as it seems to be? What happens if the distribution is skewed to one side?
Is there some truth that we need to reduce the weightage in our second language as the previous minister of education attempted to do so because the students' standard is too low or is there another reason?
I have gone out of context.
Its time to take a closer look at the frog and tadpole question. How is the marking scheme for this question? Is the examiner expecting a unique correct answer and therefore would mark all else wrong? Or is he prepared to accept all answers that are not wrong? Are the teachers communicated as to the expectation of answering open ended questions if the decision is to accept all answers that is not wrong? Are the students prepped such that they can write all reasonable answers? If the setter has intended to only accept a singular unique answer to the question according to whatever concept he imagined to be right, has he erred in not ensuring that only a single unique answer can satisfactorily answer the question?
My 2 cents worth again