Q&A - PSLE Science

[simple88]

Hi,


I’m new to the forum discussion but I have been reading and picking up a lot of useful information here. Have a P4 question from my DD which my P6 DS also does not know. I hope to get some advice here.

Nanyang 2010 SA2 P4 Q23
Kharil conducted an experiment to find out how the colour of a material affects the amount of heat absorbed by the cloth. He placed two similar blocks of ice in the basketball court and covered them with cloths of different colours. Cloth A is pink and cloth B is dark red.

Which one of the following statements is a likely hypothesis for the experiment?
1) The block of ice covered by cloth B will melt first.
2) The block of ice will melt because of heat from the sun.
3) Both blocks of ice will absorb heat from the surroundings.
4) Cloth B will release more coldness to the surroundings.

The answer key is (3) but I thought should be (1).
The definition of Hypothesis I gathered from Science PSLE Guide Book is what you predict the results of an experiment will be.

Can someone help to enlighten me? Thanks!

[Chenonceau]

simple88:

Hi,


I'm new to the forum discussion but I have been reading and picking up a lot of useful information here. Have a P4 question from my DD which my P6 DS also does not know. I hope to get some advice here.

Nanyang 2010 SA2 P4 Q23
Kharil conducted an experiment to find out how the colour of a material affects the amount of heat absorbed by the cloth. He placed two similar blocks of ice in the basketball court and covered them with cloths of different colours. Cloth A is pink and cloth B is dark red.

Which one of the following statements is a likely hypothesis for the experiment?
1) The block of ice covered by cloth B will melt first.
2) The block of ice will melt because of heat from the sun.
3) Both blocks of ice will absorb heat from the surroundings.
4) Cloth B will release more coldness to the surroundings.

The answer key is (3) but I thought should be (1).
The definition of Hypothesis I gathered from Science PSLE Guide Book is what you predict the results of an experiment will be.

Can someone help to enlighten me? Thanks!

A hypothesis describes an observable result you predict for the experiment. Only (1) is observable. You can't observe \"because of heat from the sun\". This is an explanation for why ice melts, not an event you can see.

You can't observe that the \"blocks of ice will absorb heat\". Again, this is an explanation for why ice melts, not an event you can see.

You also can't observe Cloth B releasing more coldness.

You CAN observe which block of ice melts first as described by Statement (1).

[simple88]

Thanks alot! That should clear my doubts.

[MadScientist]

I’d go for 1) as well… the basis (defines parameters) of conducting the experiment was about colour absorbtion of heat. That qualifies 1) to be the answer. 3) is the actual event that would happen… but not the aim of the experiment nor the observed parameter.

[Verysuperkiasu]

smartmummy:

i have a qn.

Is it correct to say that the stress ball can be compressed?Explain ur answer.

pls help me answer the qn.thank you.

Hmmm... it's quite tricky. Stress ball is a solid and we know solids can't be compressed as it has a definite shape and definite volume. But the fact that it can be squeezed into a smaller size it's because of the air spaces inside it (just like a sponge). So, yeah it's a good question, can we use the word 'compress' in this case???

[pixiedust]

I have 2 questions regarding syllabus of PSLE Science :


1) Is opposing batteries in the syllabus ?
2) Electricity flows from negative/positive pole to positive/negative pole - which is right ?

[Sun_2010]

pixiedust:

I have 2 questions regarding syllabus of PSLE Science :


1) Is opposing batteries in the syllabus ?
I dont know about the syllabus per se but there are plenty of questions with batteries placed opposing each other , so best to under this concept.

2) Electricity flows from negative/positive pole to positive/negative pole - which is right ?

Convention is Electricity flows from positive to the negative - always.
( even though elctrons actually flow from negative to positive)

[pixiedust]

http://i1197.photobucket.com/albums/aa424/pixie_dust8/sciq.jpg\">


Any comments about the above from MC Science PSLE Revision Guide ?

[Sun_2010]

pixiedust:

http://i1197.photobucket.com/albums/aa424/pixie_dust8/sciq.jpg\">


Any comments about the above from MC Science PSLE Revision Guide ?

Electricity is the term used for electric current. And current flows from the positive to negative. It is one of the conventions set before the structure of atom was discovered, so it was Benjamin Franklin set that the positive charge flows.
And this convention remained even though it was firmly established that it is the electrons that flow not protons.

http://en.wikipedia.org/wiki/Electric_current
this can be googled on many educational sites too

I am surprised by this highlighted point in MC PSLE revision guide.

Am I really getting obsolete

Calling experts !! :?:
tianzhu can you hear...

We need to have this sorted out, please

[Nebbermind]

Has always been the convention for current to flow from the higher potential to lower potential…u mean it has changed??