Q&A - PSLE Science

[Robertpattinsonidle]

superksmum:

charsen:

[quote=\"superksmum\"]Hi all,

Need some advice on what greenhouse effect is and how it benefits plants. Does it also have negative and positive effects?

TIA

Hi
Green house effects is the amount of green house gases like carbon dioxide in the atmosphere.These green house gases trap heat from the sun .As there are more green house gases in the atmosphere,more heat from the sun is trapped in the earth 's atmosphere.There is no positive effect on the plants due to the green house effect as far as i know.But,the negative effect is global warming an the rise of sea levels.
Charsen

Hi Charsen,
Thanks, u have been very helpful. Is global warming a negative effect also?[/quote]yes global warming is an effect

[Robertpattinsonidle]

just wanted to giv a gentle remainder.

p6 students usually do this mistake
remember: when the questions asks positively, we must answer positively.
e.g.
why did it fly?
ans: cannot be why it doesnt fly

another common error is that, when they are asking for A, we must not say why b is wrong.
if qsn asks comparison between A and B, we must giv comparison and not just one of it.
hope it helps
thanks,
robertpattinsonidle ft.JB
pls like this post :)))

[insanePaPa]

Pls enlighten me, pls.


A plastic beaker, with a hole at the bottom, is held above a waterwheel using a retort stand. Water dripping from the beaker causes the waterwheel to turn. Water drips into a dish place below. State the energy conversion that takes place.

Is this answer correct?
Gravitational potential energy (water in the beaker)--> Kinetic energy (waterwheel)--> Heat & Sound energy (water in the dish).

or this
Gravitational potential energy (water in the beaker)--> Kinetic energy (waterwheel)--> Potential energy (water in the dish).

:thankyou:

insanePaPa

[balu_priya]

How to attach scanned pdf files?

[charsen]

insanePaPa:

Pls enlighten me, pls.


A plastic beaker, with a hole at the bottom, is held above a waterwheel using a retort stand. Water dripping from the beaker causes the waterwheel to turn. Water drips into a dish place below. State the energy conversion that takes place.

Is this answer correct?
Gravitational potential energy (water in the beaker)--> Kinetic energy (waterwheel)--> Heat & Sound energy (water in the dish).

or this
Gravitational potential energy (water in the beaker)--> Kinetic energy (waterwheel)--> Potential energy (water in the dish).

:thankyou:
Hi
The answer should be
Gravitational potential energy(water in the beaker)--->kinetic energy(dripping water)--->kinetic energy+sound energy +heat energy(in the water wheel)--->gravitational potential energy(in the water)--->kinetic energy(water dripping to the dish)
Charsen.


insanePaPa

[charsen]

Hi insane papa,

The readon why i convert the heat and sound and kinetic energy to gravitational potential energy is that water driped from the water wheel,which means that it has gravitational potential energy.
Anybody has a etter explanation?
Charsen

[insanePaPa]

charsen:

Hi
The answer should be
Gravitational potential energy(water in the beaker)--->kinetic energy(dripping water)--->kinetic energy+sound energy +heat energy(in the water wheel)--->gravitational potential energy(in the water)--->kinetic energy(water dripping to the dish)
Charsen.

Hi Charsen,

Thanks for your prompt reply. The answer in the answer sheet is the 2nd one mentioned in my post. Seem like there could be various possible answerd to it?

insanePaPa

[balu_priya]

Please help. This is a prelim paper which I got from a neighbour. http://i47.tinypic.com/212a2s7.jpg\">

[Blue Dolphin]

balu_priya:

Please help. This is a prelim paper which I got from a neighbour. http://i47.tinypic.com/212a2s7.jpg\">

(3) Cup T - largest surface area

[balu_priya]

Deleted.