Q&A - PSLE Science
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44. The diagrams below show two different power stations A and B.
power station A - Fire heating up a container of water, the container is connected to a turbine which is connected to a generator.
power station B - Water in a dam, flowing into a turbine, connected to a generator.
The diagram below shows the energy conversions that takes place in the two power stations.
Potential energy –> Kinetic energy –> Kinetic energy [turbine] –> Energy X (generator) –> Energy Y (generator)
a) Identify energy X and energy Y.
Energy X __________
Energy Y __________
TIA. -
atutor2001:
Thanks!
Anyway, my answer to such a question would be :
For P4 :
It is not a light source because it cannot produce (don't use emit) on its own as the light emitted by the bulb is produced by the electric current flowing through the bulb.
For P6 :
It is not a light source because it cannot produce (don't use emit) on its own as the light emitted by the bulb is converted from electrical energy that is supplied to the bulb by batteries or other power sources. -
When heat is applied to a solid and a liquid of the same substance which expand more ? _____________
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P5G:
X should be kinetic energy and Y should be electrical energy.
Potential energy --> Kinetic energy --> Kinetic energy [turbine] --> Energy X (generator) --> Energy Y (generator)
a) Identify energy X and energy Y.
Energy X __________
Energy Y __________
TIA.
Kinetic energy of the turbine is transferred to the generator.
The kinetic energy causes the coils in the generator to turn which will then be converted to electrical energy. -
Verysuperkiasu:
When heat is applied to a solid and a liquid of the same substance which expand more ? _____________
Liquid should expand more.
When a matter gets heated, what actually happened is that the atoms/molecules inside gained energy and can vibrate further away from each other. As they vibrate further apart, the overall size of the matter will appear bigger i.e. expands.
The atoms/molecules in a solid are \"bonded\" (held together) more tightly together than that in liquid. Therefore, if equal amount of heat is gained by the same amount liquid and solid of the same material, the atoms/molecules in the liquid will be able to vibrate further away from each other than those atoms/molecules in the solid (because they are not bonded as \"tightly\" as that in solid) and will expand more than solid. -
atutor2001:
actually electricity is also not taught in P4 yet. So I doubt this question will come up in the OE section, probably in the MCQ section.
I don't think I have come across such a question because source of light is usually tested in P4 (I think) where energy is not taught yet.
Anyway, my answer to such a question would be :
For P4 :
It is not a light source because it cannot produce (don't use emit) on its own as the light emitted by the bulb is produced by the electric current flowing through the bulb.
For P6 :
It is not a light source because it cannot produce (don't use emit) on its own as the light emitted by the bulb is converted from electrical energy that is supplied to the bulb by batteries or other power sources. -
Hi All,
MGS 2011 P6 Prelim Science paper is http://mwtuition.com.sg/free-resources but no answers are given. :please: help to check my younger sister's answers for the 30 MCQs of this paper. TIA.
Q1. Option 2
Q2. Option 3
Q3. Option 2
Q4. Option 4
Q5. Option 3
Q6. Option 4
Q7. Option 3
Q8. Option 1
Q9. Option 3
Q10. Option 3
Q11. Option 4
Q12. Option 2
Q13. Option 2
Q14. Option 1
Q15. Option 3
Q16. Option 4
Q17. Option 4
Q18. Option 4
Q19. Option 3
Q20. Option 4
Q21. Option 1
Q22. Option 3
Q23. Option 1
Q24. Option 4
Q25. Option 2
Q26. Option 3
Q27. Option 1
Q28. Option 2
Q29. Option 3
Q30. Option 4
If you disagree with any of the above suggested answers, pls advise the correct answers. OK and cheers. :snuggles: -
Please help.
44. Karen used two set-ups, A and B, for her experiments.She added baking soda to the water in one of the set-ups to increase the concentration of carbon dioxide. She then placed them in the sun.
Pictures of the 2 set-ups given [A beaker of water with a hydrilla in it. An upside funnel is over the hydrilla and a test tube full of water over the funnel. Both set-ups were exactly the same].
The table below shows the number of bubbles produced in the 2 set-ups over 20 minutes.
Time (min) | Number of bubbles produced
-------------| Data set X | Data set Y
(0) | Data set X (0) | Data set Y (0)
(5) | Data set X (3) | Data set Y (4)
(10) | Data set X (9) | Data set Y (11)
(15) | Data set X (13) | Data set Y (17)
(20) | Data set X (19) | Data set Y (25)
a) Which set of data, X or Y, represents the result from the set-up with baking soda added? Explain your answer.
b) Besides the amount of hydrilla, state another variable which can be changed for the set-ups to have similar results as the table shown.
.
TIA. -
John filled a bottle with water to the brim and placed it in the freezer. Two hours later, he observed that the water had frozen and the bottle had cracked. Which statement has correctly explained what had happened?
(1) The bottle was not able to withstand the low temperature causing it to crack.
(2) The water expanded during freezing pushed outwards and caused the bottle to crack
(3) The water contracted during freezing, pushed outwards and caused the bottle to crack.
(4) When the water froze to ice, it got heavier and the bottle could not withstand the weight, causing the bottle to crack.
My question : According to my son, none of the above 4 obtions seem to fit coz his answer is :
‘The bottle contracts faster than the ice inside it therefore it cracked’. What is the answer and why? -
atutor2001:
Got it , thanks so much
The atoms/molecules in a solid are \"bonded\" (held together) more tightly together than that in liquid. Therefore, if equal amount of heat is gained by the same amount liquid and solid of the same material, the atoms/molecules in the liquid will be able to vibrate further away from each other than those atoms/molecules in the solid (because they are not bonded as \"tightly\" as that in solid) and will expand more than solid.
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