Q&A - PSLE Science

[balu_priya]

charsen:

balu_priya:

Please help. My guidebook mentions that balances measure mass not weight http://i50.tinypic.com/9fo5tz.jpg\"> but the given answer is option .

It is option 3 but why? :?: :thankyou:

[mamago]

charsen:

ALL THE BEST TO ALL PSLE STUDENTS FOR THE SCIENCE EXAM TMRW.

:thankyou: Charsen. You have been very helpful...

[charsen]

paranoid:

please help with this question :?: :imdrowning:

http://i48.tinypic.com/2j3ikwi.png\">

Thanks in advance

Ans 1

Option D is not possible as earthworm has a segmented (muti segments) body.

[creamyhorror]

balu_priya:

charsen:

[quote=\"balu_priya\"]Please help. My guidebook mentions that balances measure mass not weight http://i50.tinypic.com/9fo5tz.jpg\"> but the given answer is option .

It is option 3 but why? :?: :thankyou:[/quote]Double-pan balances like that one in the picture actually measure weight. They literally balance the two weights against each other. In space, things are weightless, and the objects would just float without exerting any force on the pans. Thus the beam would remain horizontal (option 3). This is because in space, there's no huge gravitational force pulling the objects down towards the centre of the Earth. That force is what we call \"weight\".

Your guidebook probably says \"balances measure mass\" because the numbers that balances give are in units of mass, e.g. 30kg. But balances are actually measuring weight and providing mass values equivalent to that weight. (edit) Balances will measure mass as long as there is a gravitational force acting on both objects (e.g. when you're on Earth or on another planet). In space there isn't any major gravitational force, so balances won't work properly.

[Petkwang]

http://i47.tinypic.com/scyjgz.jpg\"> Please assist to provide answer. Thank you!

[Haneyi]

Hello, answer should be 3.


C is quite obvious from the set-up – you can see that the south poles of both magnets are facing each other.

Should magnetic force be able to pass through the thin copper sheet, the magnets - being like poles, would repel each other and not be attracted in the direction of the thin copper sheet. Therefore, we conclude that A is wrong and B is correct.

Please correct me if I’m wrong and feel free to ask more questions if you have any.

Hope this helps.

> Also, please refrain from creating duplicate threads. ^^

[Petkwang]

Thank you :celebrate:

[Petkwang]

Thank you :celebrate:

[Haneyi]

charsen:

paranoid:

please help with this question :?: :imdrowning:

http://i48.tinypic.com/2j3ikwi.png\">

Thanks in advance

Ans 1

Option D is not possible as earthworm has a segmented (muti segments) body.

Yes, that's what I think too. Option C is also not possible as the animals there do not breathe through breathing holes. ^^

[creamyhorror]

Haneyi:

charsen:

[quote=\"paranoid\"]please help with this question :?: :imdrowning:

http://i48.tinypic.com/2j3ikwi.png\">

Thanks in advance

Ans 1

Option D is not possible as earthworm has a segmented (muti segments) body.

Yes, that's what I think too. Option C is also not possible as the animals there do not breathe through breathing holes. ^^[/quote]I checked my brother's PSLE guidebook and it doesn't mention which animals breathe through breathing holes. I researched online and it turns out that many/most insects, including ladybirds and butterflies, breathe through breathing holes (spiracles). It also turns out that snails have a breathing hole, but it's probably a different type from insects'.

Is this information even in the syllabus? Surely no one would know if snails have breathing holes.