Q&A - P5 Science

[Trevortan]

PSLEguru:

Trevortan:

[quote=\"Trevortan\"]

http://i44.tinypic.com/28sm2j6.jpg\">

Pls help!!!

i think:
(a) to find out if germination of seeds results in a change in temperature.
(b) to kill the peas so they won't germinate. it's boiled instead of roasted to keep everything as much as possible the same - i.e. using water, one is soaked and one is boiled.[/quote]Hi PSLEguru,
If Flask B is used as a constant/baseline, then why bother to kill the peas when you can just put in a thermometer without anything else in the flask? Besides, they are finding out if germination of seeds results in a change in temperature, so why would they want to kill the seeds? :scared:

[Jamesbond]

http://i40.tinypic.com/1zbtod2.jpg\">


The question given is
a) what would happen to the iron rod and the paper clips?
The iron rod would become an electromagnet and attract the paper clips.

b) what will happen to the iron rod if the batteries are reversed before closing the switch?

For this question only, I need answer.

Ans 1. The iron rod will not attract paper clips anymore.
Ans 2. The iron rod will attract lesser paper clips.

Can anybody help and confirm whether ans 1 is better or ans 2 is better?

Which is correct?

[StudyRoom]

Trevortan:

Hi PSLEguru,
If Flask B is used as a constant/baseline, then why bother to kill the peas when you can just put in a thermometer without anything else in the flask? Besides, they are finding out if germination of seeds results in a change in temperature, so why would they want to kill the seeds? :scared:

Hi,

If you don't have anything else in the flask, you don't know if the temperature change is due to the water or the peas. Maybe it is something else that is causing the temperature change, such as, say, the peas decomposing.

So you need live seeds and killed seeds. The live seeds will germinate and the killed ones won't.

[XXXX]

Jamesbond:

http://i40.tinypic.com/1zbtod2.jpg\">


The question given is
a) what would happen to the iron rod and the paper clips?
The iron rod would become an electromagnet and attract the paper clips.

b) what will happen to the iron rod if the batteries are reversed before closing the switch?

For this question only, I need answer.

Ans 1. The iron rod will not attract paper clips anymore.
Ans 2. The iron rod will attract lesser paper clips.

Can anybody help and confirm whether ans 1 is better or ans 2 is better?

Which is correct?

what will happen to the iron rod if the batteries are reversed before closing the switch?

Ans 2 is better. The rod will retain some magnetism when the circuit is open (i.e. before closing the switch).

Correct English would be \"fewer\", not \"lesser\".

[Jamesbond]

XXXX:

Jamesbond:

http://i40.tinypic.com/1zbtod2.jpg\">


The question given is
a) what would happen to the iron rod and the paper clips?
The iron rod would become an electromagnet and attract the paper clips.

b) what will happen to the iron rod if the batteries are reversed before closing the switch?

For this question only, I need answer.

Ans 1. The iron rod will not attract paper clips anymore.
Ans 2. The iron rod will attract lesser paper clips.

Can anybody help and confirm whether ans 1 is better or ans 2 is better?

Which is correct?

what will happen to the iron rod if the batteries are reversed before closing the switch?

Ans 2 is better. The rod will retain some magnetism when the circuit is open (i.e. before closing the switch).

Correct English would be \"fewer\", not \"lesser\".

:thankyou:

[Jamesbond]

Are red blood cells involved in clotting of blood or not?

[StudyRoom]

Jamesbond:

Are red blood cells involved in clotting of blood or not?

Good question. The blood clotting process is quite complicated. To summarise, both platelets and fibrin first forms the clot. These form a web that traps more platelets, fibrin and other cells, red blood cells included. In this sense, red blood cells are passively involved in the clotting process, although they are not necessary in the clotting of blood.

There's also some new research which suggests that red blood cells can be actively involved in blood clotting - however I think this is not in the syllabus. http://www.ncbi.nlm.nih.gov/pubmed/10088636

Short answer: Yes, they are involved (albeit passively).

[Jamesbond]

http://i41.tinypic.com/mi0v2u.jpg\">

Sorry pic got cut below...
Suggest how Suhaila can calculate the amount of the force mentioned in (b).

Can somebody help me to answer (c)

[XXXX]

Jamesbond:

http://i41.tinypic.com/mi0v2u.jpg\">

Sorry pic got cut below...
Suggest how Suhaila can calculate the amount of the force mentioned in (b).

Can somebody help me to answer (c)

Should just be the difference in the readings on the spring balance with and without the sand. The difference is the friction force of the sand on the stick.

Cool experiment.

[Jamesbond]

XXXX:

Jamesbond:

http://i41.tinypic.com/mi0v2u.jpg\">

Sorry pic got cut below...
Suggest how Suhaila can calculate the amount of the force mentioned in (b).

Can somebody help me to answer (c)

Should just be the difference in the readings on the spring balance with and without the sand. The difference is the friction force of the sand on the stick.

Cool experiment.

:thankyou: