Saturday, October 9, 2010 ; 6H's Questions
Kieron:
There is a circuit, in the circuit, there is a battery and 2 bulbs in a series arrangement. If one of the bulb fuses, will the other bulb still light up? If your answer is no, I would like to know the reason as the metal casing of the fused bulb can still act as a conductor for the electricity to flow around it and close the circuit.
If one of the wires is at the metal tip and the bulb fuses, it becomes an open circuit. However, if the metal casing is linked to two wires, it is an electrical conductor regardless of whether it has fused.
Glennis:
As for question number 15 of this paper, why does Bulb P lights up? I thought when Q fuses, P will fuse as well since they're of series arrangement?
http://www.misskoh.info/07/primary6-rosyth-science.pdf
Good question. This question is testing whether you know metal casing of bulb is a conductor of electricity. Bulb Q wasn't connected at the metal tip but at the metal casing by 2 wires. So whether it fuses or not, electricity will flow through its metal casing.
Good question. This question is testing whether you know metal casing of bulb is a conductor of electricity. Bulb Q wasn't connected at the metal tip but at the metal casing by 2 wires. So whether it fuses or not, electricity will flow through its metal casing.
For question 10 of this paper, why is the answer 3???
First of all, the changes in volume of water when it changes state is out of syllabus. When water freeze, its volume increases. That's why ice will pop out of your ice tray. When ice melts, volume expands back. Ans is 4, not 3
First of all, the changes in volume of water when it changes state is out of syllabus. When water freeze, its volume increases. That's why ice will pop out of your ice tray. When ice melts, volume expands back. Ans is 4, not 3
And question 22, why is the answer not 2?
Hot air can move things but in this case, this toy doesn't use hot air, it uses our strong blow to move the toy. So, it is a push from the breath we blow and it can overcome the weight of the ball. Moreover, they wrote about the ball gets heated and rise, not hot air pushing it in (2). We're mammals, we're warm blooded but we don't rise hehe
Hot air can move things but in this case, this toy doesn't use hot air, it uses our strong blow to move the toy. So, it is a push from the breath we blow and it can overcome the weight of the ball. Moreover, they wrote about the ball gets heated and rise, not hot air pushing it in (2). We're mammals, we're warm blooded but we don't rise hehe
Question 25, is bronze a magnetic material? What about mercury and alcoholic?
None of the above. Only steel and iron are magnetic in your syllabus. The other magnetic materials are cobalt and nickel.
None of the above. Only steel and iron are magnetic in your syllabus. The other magnetic materials are cobalt and nickel.
As for question 26. How to see which switches are needed to be close? Are the switches in parallel same as those in series?
Arrangement of switches does not matter but the location matters as it can make a whole circuit or part of a circuit open. For this question, test all options and check whether the current from the batteries can flow from the positive terminal to the negative one.
(1) A, B, D --> 2 bulbs light up
(2) A,B,C,D --> Still same 2 bulbs light up or there might be a short circuit skipping 1 of the bulbs.
(3) A,B,D,E --> all bulbs
(4) A,B,C,D,E --> all bulbs
I would say both 1 and 2 are correct but 1 is the best of all answers.
Arrangement of switches does not matter but the location matters as it can make a whole circuit or part of a circuit open. For this question, test all options and check whether the current from the batteries can flow from the positive terminal to the negative one.
(1) A, B, D --> 2 bulbs light up
(2) A,B,C,D --> Still same 2 bulbs light up or there might be a short circuit skipping 1 of the bulbs.
(3) A,B,D,E --> all bulbs
(4) A,B,C,D,E --> all bulbs
I would say both 1 and 2 are correct but 1 is the best of all answers.
Explain question 27 and 28. Why is the answer for 28 not 2?
For 27, firstly, you can't compare things of different units, so (2) and (3) are out. Light energy converts to heat energy, so (4) is out. Light energy converts to heat energy in water (a matter) while vibrating fork emits sound energy to convert to KE of water (matter), so (1) is the answer.
For 28, it's a solar cooker, so it's making use of heat energy from the sun to cook something. (1) and (3) have nothing to do with energy, so they're out. (2) is reflecting the light energy away, so heat energy is reflected too, how to cook?? (4) channels the sun's heat energy into the beaker of water to cook whatever's in the water.
For 27, firstly, you can't compare things of different units, so (2) and (3) are out. Light energy converts to heat energy, so (4) is out. Light energy converts to heat energy in water (a matter) while vibrating fork emits sound energy to convert to KE of water (matter), so (1) is the answer.
For 28, it's a solar cooker, so it's making use of heat energy from the sun to cook something. (1) and (3) have nothing to do with energy, so they're out. (2) is reflecting the light energy away, so heat energy is reflected too, how to cook?? (4) channels the sun's heat energy into the beaker of water to cook whatever's in the water.
In view of the answer for question 30, does it mean that if the magnet is further from the bottom magnet, it is stronger? But i thought the bottom one is suppose to be stronger? Since they have the same mass, why isn't the answer 4?
The further the magnets, the stronger the force of repulsion PROVIDED you did not change the bottom magnet or the top magnet for comparison. So, you can conclude that A is stronger than C based on set-ups 2 and 3 (same bottom magnet, D). B is stronger than D (same top magnet in set-ups 1 and 3). So, only 2 conclusions on strengths of magnets can be drawn.
The further the magnets, the stronger the force of repulsion PROVIDED you did not change the bottom magnet or the top magnet for comparison. So, you can conclude that A is stronger than C based on set-ups 2 and 3 (same bottom magnet, D). B is stronger than D (same top magnet in set-ups 1 and 3). So, only 2 conclusions on strengths of magnets can be drawn.
-For dispersal of seeds, how can i know that they are dispersed by animals? Is it because they crowd together? Wait, crowding together is for splitting or..??
By animals, the seeds are randomly scattered all over usually.
-Is nuclear a renewable source of energy?
Can be renewable but mostly non-renewable but nuclear energy is out of syllabus.
By animals, the seeds are randomly scattered all over usually.
-Is nuclear a renewable source of energy?
Can be renewable but mostly non-renewable but nuclear energy is out of syllabus.
-Which comes first--- pollination, fertilisation, germination, seed dispersal, development, flower reproduction?
None as plant life follows a cycle. It's like asking whether the egg or the chicken existed first. Say i start from seed germination, it develops into a plant with flower, then flower gets pollinated and becomes fruit. Fruit has seed for dispersal. Seed germinates and this cycle continues.
None as plant life follows a cycle. It's like asking whether the egg or the chicken existed first. Say i start from seed germination, it develops into a plant with flower, then flower gets pollinated and becomes fruit. Fruit has seed for dispersal. Seed germinates and this cycle continues.
-If 3 seeds are placed on damp cotton wool in a beaker and the beaker is placed in a cardboard box, will the seeds still be able to germinate?
Yes. it doesn't need light to germinate, just 3 conditions: water, oxygen, warmth (no need sunlight)
Yes. it doesn't need light to germinate, just 3 conditions: water, oxygen, warmth (no need sunlight)
- If 2 groups of fruits are edible and are eaten by animals, but have a different way of how their seeds are scattered, how to differentiate them?
e.g. mango and papaya= group 1. inedible seeds
Cucumber and tomato = group 2. small and edible seeds
-Is it true that when there is more water, more heat will be transferred?
Depends on the surrounding. Heat travels more if the temperature difference is wider but water is a poor conductor of heat.
Is it true that air is a better conductor of heat than water? Air is better than water in conducting heat.Depends on the surrounding. Heat travels more if the temperature difference is wider but water is a poor conductor of heat.
If its true, what about electricity? Which is better? Water conducts electricity (not pure water though), air does not conduct electricity.
PSLE Booklet, page 55, question 8, I thought when GPE is highest at the two ends, it will decrease when the boy touches the ground? Why did the potential energy plotted at the graph increase instead of decreasing???
I don't have the PSLE booklet with me now. But if it is the swing question, GPE is zero when boy touches the ground as height from ground is zero. Did you read the answer wrongly?
I don't have the PSLE booklet with me now. But if it is the swing question, GPE is zero when boy touches the ground as height from ground is zero. Did you read the answer wrongly?
PSLE booklet, specimen paper, question 22. I thought height from the ground at A is higher than B, GPE should increase right? Why is the answer 2 not 3??
Is it the skater question? At a higher height, GPE ought to be higher. You're right. Wish i have the book with me.
Is it the skater question? At a higher height, GPE ought to be higher. You're right. Wish i have the book with me.
-Does all young of an animal/ insect that go through the 3-stage life cycle looks like its parents?
For insects, most of them. At least I've yet to see one that doesn't look like parent.
For insects, most of them. At least I've yet to see one that doesn't look like parent.
- Gravity is dependent on mass only right? Does it depend on height?
Force of gravity is dependent on mass. It does not depend on height. Just remember, is it harder to walk on the 50th floor? It's just as easy as walking on the 1st floor, so force of gravity did not increase as you go higher or lower. But GPE is dependent on height and remember that GPE is energy waiting to convert to other energy, usually KE.
Force of gravity is dependent on mass. It does not depend on height. Just remember, is it harder to walk on the 50th floor? It's just as easy as walking on the 1st floor, so force of gravity did not increase as you go higher or lower. But GPE is dependent on height and remember that GPE is energy waiting to convert to other energy, usually KE.
posted by Allan at
10:33 PM
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