Q&A - P3 Science

[elkniwt]

Hi Tianzhu,


My dd's ans for the qn i asked is 4 (the one without the outline for the transparent plastic).

Here's another qn Q19 for this paper
http://www.orlesson.org/orp/09Sc/P4-09-Sc-SA1-RGS.pdf

The third shadow (triangle) only shows triangle cos the circle object is transparent and does not cast shadow. If need to draw outline for transparent object, then around the triangle, there should be a circle outline.

So, I am very confused, teach her until I also blur.

Regards.

[tianzhu]

elkniwt:

Dear tianzhu,


Thank you for your quick reply. But may I know how come for the clear plastic which is transparent, it is necessary to draw the outline? My dd said teacher taught that transparents objects do not cast shadow.

Thanks for help. It is kind of confusing for me and the child cos for some papers, the outlines of transparent objects are not drawn, but for this qn the correct ans is the one with the outline drawn.

Hi elkniwt

The outline shows the transparent object (clear plastic) as one looks through it to see the shadow formed by the mini hoop and frosted glass.

Option (1) is a logical answer if one stands at the position of the torch and look through the clear plastic.

For this question, we should take note that the clear plastic is of much bigger size as compared to the frosted glass.Thus one needs to look through the plastic when the eyes are at the same level as the the position of the torch.

Please take a piece of clear glass/plastic of the same size as a piece of A4 paper and place it before a piece of smaller opaque cardboard, you should be able to see why.You have to look through the glass/plastic as it is much bigger.

Try to look at the context of the question and choose the appropriate answer.

Best wishes

[tianzhu]

Hi elkniwt


For Q19,try to relate to the context of the question.

In this question, the types of shadows formed are shown in the question, and we should draw conclusion from them without additional inputs.

If you want to look for a reason, you may look at it this way, but it’s not needed to answer this question.

The sizes of the objects are small, about 2cm, about the size of a 20 cents coin; it should not block the angle of the eyes while looking at the shadows. Try looking at a 20 cents coin.

Option(4) is a logical answer.

Best wishes

[atutor2001]

elkniwt:

Hi,


I refer to Qn 10 in this paper,
http://www.orlesson.org/orp/09Sc/P4-09-Sc-SA2-HenryPark.pdf

For this type of question, is it necessary to draw the outlines of transparent objects for the shadows?

Regards

I will choose 4 as the answer.

[iFruit]

atutor2001:

elkniwt:

Hi,


I refer to Qn 10 in this paper,
http://www.orlesson.org/orp/09Sc/P4-09-Sc-SA2-HenryPark.pdf

For this type of question, is it necessary to draw the outlines of transparent objects for the shadows?

Regards

I will choose 4 as the answer.

Yes. (4) is the right option.

Transparent means it shouldn't make a difference whether you put the light source before or after clear plastic ( but before frosted glass ). So (4) is the right option.

[the little little girl]

hi! how to do tis question??????????????????? :?:


Sumei poured water of different temperatures and amount into four glasses. Which glass has the most amount of heat?

1)volume of water: 100ml, 20 deg
2)Volume of water: 90ml, 30deg
3)Volume of water: 100ml, 40deg
4)Volume of water: 90ml, 80deg

option 4 more heat or option 3 more heat?
if volume is 90ml and 50deg, is it more than 3 or less? :? :imdrowning:

[the little little girl]

Hi,

i got a different ans from the ans key for tis question :

There are two identical beakers , A and B, each containing 300ml of water and the same volume of oil. Xianne put a plant in beaker B and placed both beakers on a table near the window.

Xianne took the plant out from Beaker B after 3 days. Which one of the followinh shows the likely amount of water left in the two beakers at the end of the experiment?

1) A=300ml, B=300ml
2) A=250ml, B=280ml
3) A=300ml, B=250ml
4) A=280ml, B=250ml

i chose 3 but ans is 4. Why? :? :scratchhead: :gloomy: :idea:

[ET-PH]

the little little girl:

hi! how to do tis question??????????????????? :?:


Sumei poured water of different temperatures and amount into four glasses. Which glass has the most amount of heat?

1)volume of water: 100ml, 20 deg
2)Volume of water: 90ml, 30deg
3)Volume of water: 100ml, 40deg
4)Volume of water: 90ml, 80deg

option 4 more heat or option 3 more heat?

My ans is 4. This is because ans 4 has the highest temperature and the least amount of water.
[quote] if volume is 90ml and 50deg, is it more than 3 or less? [/quote]

If the volume is 90ml and 50deg, it is difficult to decide between ans 3 and this option (too close). Hope school wouldn't set questions like this.

[ET-PH]

the little little girl:

Hi,

i got a different ans from the ans key for tis question :

There are two identical beakers , A and B, each containing 300ml of water and the same volume of oil. Xianne put a plant in beaker B and placed both beakers on a table near the window.

Xianne took the plant out from Beaker B after 3 days. Which one of the followinh shows the likely amount of water left in the two beakers at the end of the experiment?

1) A=300ml, B=300ml
2) A=250ml, B=280ml
3) A=300ml, B=250ml
4) A=280ml, B=250ml

i chose 3 but ans is 4. Why? :? :scratchhead: :gloomy: :idea:

My ans is 3. The layer of oil prevents evaporation (Theory), thus A is equal to 300ml. The plant in beaker B will absorb the water, so the amount of water should be lower than beaker A (300ml).

My guess on why the answer key is 4 is because it assumes that there is some evaporation (when it's placed near the window) even though there is a layer of oil.

I am no expert in Science, picking up the knowledge while i teach my dd. Any experts please feel free to correct me. Thanks.

[atutor2001]

ET-PH:

the little little girl:

hi! how to do tis question??????????????????? :?:


Sumei poured water of different temperatures and amount into four glasses. Which glass has the most amount of heat?

1)volume of water: 100ml, 20 deg
2)Volume of water: 90ml, 30deg
3)Volume of water: 100ml, 40deg
4)Volume of water: 90ml, 80deg

option 4 more heat or option 3 more heat?

My ans is 4. This is because ans 4 has the highest temperature and the least amount of water. incorrect

The answer is 4. How to check :
100 x 40 = 4000
90 x 80 = 7200

The product is (proportional to) an indication of the amount of heat (a shortcut you may wish to teach your kid)