Q&A - P3 Science

[shurley197323]

I check with the internet, the common material for school bag are canvas, polyester, nylon and PVC.

[ChiefKiasu]

shurley197323:

I check with the internet, the common material for school bag are canvas, polyester, nylon and PVC.

At the prices some of these bags are going for these days, I think school bags are made from paper money and plastic credit cards. And lot's of parents' sweat and tears.

[jesschan]

ChiefKiasu:

shurley197323:

I check with the internet, the common material for school bag are canvas, polyester, nylon and PVC.

At the prices some of these bags are going for these days, I think school bags are made from paper money and plastic credit cards. And lot's of parents' sweat and tears.

Ha ha!

Jokes aside, I just thought that though it is not common to use leather for school bags, it is not entirely wrong because bags can be made from leather and leather bags can be used by mature students as school bags.

Anyway, thanks!

[corneyAmber]

ChiefKiasu:

shurley197323:

I check with the internet, the common material for school bag are canvas, polyester, nylon and PVC.

At the prices some of these bags are going for these days, I think school bags are made from paper money and plastic credit cards. And lot's of parents' sweat and tears.

haha...can't agree more....that debunks all normal science....should be social science.

[Vanilla Cake]

Hi All,


TIA for your time and effort to answer this P4 SA1 2008 SCGS Q26 :

Coleen conducted an experiment by measuring the length of her shadow on the ground at different time intervals over one day. She remained at the same spot for the whole duration. The following graph shows her findings.

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(a) What is the relationship between the length of the shadow and the time of the day (1 mark)

(b) Explain your answer in (a) (1 mark)
Suggested answer given by the worksheet is confusing. :? Pls see below :

(a) The length of the shadow gets shorter the time is nearer to 12.00 pm and increases again after 12.0pm

(b) The sun moves from the east to the west. At 12.00 pm the sun is directly overhead but at 8.00 am and 6.00 pm, it is low in the sky.

[tianzhu]

Hi VC


First, let us recap the concepts behind this question which is from the topic, Light (current PSLE Science syllabus).

Shadows
A shadow is made when an object blocks light. Opaque objects make dark shadows. Translucent objects make faint shadows.

Shadows made by the sun
The sun is a very bright natural light source. It rises in the East and sets in the West. The sun casts longest shadows at the beginning and end of the day, when the sun is lowest in the sky. The sun casts shortest shadows at midday, when the sun is highest in the sky.

Going further, it’s good to know how a shadow changes when the properties (brightness, position,) of a light source are changed.

My suggested responses to Q1 are,

(a) From the graph, the length of shadow decreases when the time moves from 0800hrs to 1200hrs .The shadow is shortest at 1200hrs.After that, the length of shadow increases as the time moves towards 1800hrs.

As for (b), The sun casts longest shadows at the beginning and end of the day, when the sun is lowest in the sky. The sun casts shortest shadows at midday, when the sun is highest in the sky.

Hope this is of some use to you.

[Vanilla Cake]

Hi All,

This P4 Science Qn is from Ai Tong School SA1 2008 Q8:

A football can hold 350 cm3 of air. Esther used a syringe and drew out 20 cm3 of air from the football. The volume of air in the football would be :

(1) 320 cm3
(2) 330 cm3
(3) 350 cm3
(4) 370 cm3

Worksheet’s answer is (3). Is this correct and why ?
Thks in advance for your reply and time.

[tianzhu]

Hi VC


Air is a matter with no fixed volume and no fixed shape. It compresses or expands to take the shape of the container holding it.
Yes the WS’s answer is correct.

[jesschan]

I think the answer depends on whether the football is hard or deflatable. If it is deflatable, then 350cm3 will not be correct. Are the kids being taught about atmospheric pressure?

[Joy]

Hi there


Since we are on the topic of science, jsut wonder, can someone share with me is there one conscise guide book in the market/I used to know there is one printed by eph but its no longer around.thanks