puff:

lee_yl:

[quote=\"nicnac\"]Wood, some float and some sink..

Although both are metals, when your hubby gives you a ring, either a gold ring or copper ring, would you think both are the same?

[/quote]If you love him enough you would think both are the same

lee_yl:

nicnac:

Wood, some float and some sink..

Although both are metals, when your hubby gives you a ring, either a gold ring or copper ring, would you think both are the same?

Sivak222:

Even if the solid metal ball can float on water due to surface tension and with precise calculations, say diameter must not exceed 2.6cm, then how can balls Y and Z made of the same material and identical, one end up floating and one sinking?


This question just wanted to test on the P3 material topic, and density is not within the PSLE syllabus.

Agree that ans 2 shouldn't be wrong if base on the p3 material topic tat is being taught. However ans 4 shouldn't be wrong either as there are too many possibility tat 2 same material can float or sink.

Floating due to surface tension can make material either float or sink .if u throw in the material with force it will sink ...if u place it gently enuff it will float ....mostly this experiment is done using needle but with very precise calculation it can be done on ball too.
Don't know if it is applicable to their sci qn but like i says too many possibility for this qn hence hard to says ans 4 is wrong.

What abt cotton ball ...1 cotton ball could have placed in the water first when it sink i place another cotton ball in hence the image of 1 floating cotton ball n 1 sink cotton ball.[/quote]

From Primary 3 material topics students learned only ability to float or sink. They give some examples for floating materials and some examples for sinking materials. Basic science teach only some type of materials float on water and some other types sink on water. Two solids sink one float means they want to know one type material like steel ball will sink and other type material like styrofoam ball will float. Not necessary to think density, surface tension. These are out of topics. Question will be within in the syllabus. I studied many primary science books before I teach my child, all books covered only material either float or sink. If we study general science topics we can consider other factors. Thanks.[/quote]

Did they learn under material eg plastic material or wood material there are different type of plastic/ wood material which may have diff outcome of the experiment. I think they learn gerneral classification of material hence diff wood or plastic to them is still under same material type.
Anyway i do hope that some teacher or tutor can shed some light on this qn.

lee_yl:

puff:

[quote=\"lee_yl\"]I am curious why that school teacher and tutor say it’s choice (4).


Btw, a sponge soaked with water is call a solid+liquid mixture. And can a solid ball be hollow, strictly speaking, no, else we are just playing with words

Thanks for the clarify a soaked sponge ball is not consider a solid. Steel solid ball could float on water due to
surface tension with precise calculation. So same material solid ball could sink or float depending on how it is place in the water. This sci qn have too many possibility how to say ans 4 is wrong.

Even if the solid metal ball can float on water due to surface tension and with precise calculations, say diameter must not exceed 2.6cm, then how can balls Y and Z made of the same material and identical, one end up floating and one sinking?

This question just wanted to test on the P3 material topic, and density is not within the PSLE syllabus.[/quote]Agree that ans 2 shouldn't be wrong if base on the p3 material topic tat is being taught. However ans 4 shouldn't be wrong either as there are too many possibility tat 2 same material can float or sink.

Floating due to surface tension can make material either float or sink .if u throw in the material with force it will sink ...if u place it gently enuff it will float ....mostly this experiment is done using needle but with very precise calculation it can be done on ball too.
Don't know if it is applicable to their sci qn but like i says too many possibility for this qn hence hard to says ans 4 is wrong.

What abt cotton ball ...1 cotton ball could have placed in the water first when it sink i place another cotton ball in hence the image of 1 floating cotton ball n 1 sink cotton ball.

Iluvmygals:

The more we discuss about the ball question the more it looked like a PHD entrance exam....not a PSLE.

:laugh:

lee_yl:

I am curious why that school teacher and tutor say it’s choice (4).


Btw, a sponge soaked with water is call a solid+liquid mixture. And can a solid ball be hollow, strictly speaking, no, else we are just playing with words

Thanks for the clarify a soaked sponge ball is not consider a solid. Steel solid ball could float on water due to
surface tension with precise calculation. So same material solid ball could sink or float depending on how it is place in the water. This sci qn have too many possibility how to say ans 4 is wrong.

lee_yl:

Take time to analyse what does choice (4) mean. If it’s neither A nor B then it means that either “all 3 materials are the same” or “materials X and Y different and materials Y and Z same”


I would like to know what materials, when used to fabricate 3 solids (identical in everything), when submerged in water, one piece will float and the other will sink!

Depends on the definition of same material.
From their text they learn wood material plastic material glass material. However wood can be different type of wood some would sink n some would float. So does different type of wood consider same material or diff matterial?

Depends on the definition of solid ball
If a hollow ball is consider a solid ball?

I would definitely think the ans is 4( however i hope moe can accept both 2 and 4 as correct answer base on the what is taught in sch)

Eg. Both ball y and z could be make up of sponge . One float and the others sink , could it be one ball is soak with water hence mass increase therefore sink?

Wonder which is the model ans from moe?

lee_yl:

Take time to analyse what does choice (4) mean. If it’s neither A nor B then it means that either “all 3 materials are the same” or “materials X and Y different and materials Y and Z same”


I would like to know what materials, when used to fabricate 3 solids (identical in everything), when submerged in water, one piece will float and the other will sink!

Depends on the definition of same material.
From their text they learn wood material plastic material glass material. However wood can be different type of wood some would sink n some would float. So does different type of wood consider same material or diff matterial?

Depends on the definition of solid ball
If a hollow ball is consider a solid ball?

I would definitely think the ans is 4( however i hope moe can accept both 2 and 4 as correct answer base on the what is taught in sch)

Eg. Both ball y and z could be make up of sponge . One float and the others sink , could it be one ball is soak with water hence mass increase therefore sink?

Wonder which is the model ans from moe?

ski:

faithj:

I think it is 4.

eg. Y and Z could both be made of wood, but Z could be hollow.

Btw, wood does not sink

Some wood sink eg cocobolo Ebony
There is a youtube video

ski:

Should be B Only.


X and Y can be different or same materials e.g. both can be iron or X can be iron and Y is glass. There is no way to ascertain. But Z and Y must be different materials e.g. Z is wood, Y is iron.

Could Z and Y made up of different type of wood?