Physics, Chemistry and Biology: Post your doubts here!

[waleed82]

Oh, I just realized you couldn’t view the [picture] answer in my previous post!

Can you now?

View attachment 5780

oh yea thankz alot>>>>>>>>

 

[Lilpumpkin]

Hey guys i have a doubt its kinda confusing
Q)using a scale of 1cm to represent 10N find the size and direction of the resultant force of forces of 30N and 40N acting on right angles to each other.....
help anyone?

 

[Iridescent]

Q: The resistance of a coil of wire is 6.2ohms and its length is 1.0m. Using only 1.0m lengths from the same reel, without cutting any of them, state how you would produce a resistance of
(i) 3.1ohms
(ii) 12.4ohms

 

[hassankhan]

can anyone help me with physics nov2010 extended pp 31 q 11

 

[ktc]

Hey guys i have a doubt its kinda confusing
Q)using a scale of 1cm to represent 10N find the size and direction of the resultant force of forces of 30N and 40N acting on right angles to each other.....
help anyone?

You need to draw it. Use the parallelogram rule, to get the resultant force.

Q: The resistance of a coil of wire is 6.2ohms and its length is 1.0m. Using only 1.0m lengths from the same reel, without cutting any of them, state how you would produce a resistance of
(i) 3.1ohms
(ii) 12.4ohms

(i) Connect two of the 1m length wires in parallel; it will make the resistance half of the original value, from 6.2 to 3.1 ohms.

(ii) Connect two of the 1m length wires in series, which double the resistance from 6.2 to 12.4 ohms.

can anyone help me with physics nov2010 extended pp 31 q 11

Link?

 

[hassankhan]

plz help me its urgent

 

[Peaceful]

Q: The resistance of a coil of wire is 6.2ohms and its length is 1.0m. Using only 1.0m lengths from the same reel, without cutting any of them, state how you would produce a resistance of
(i) 3.1ohms
(ii) 12.4ohms

HELP someone!

 

[Iridescent]

You need to draw it. Use the parallelogram rule, to get the resultant force.


(i) Connect two of the 1m length wires in parallel; it will make the resistance half of the original value, from 6.2 to 3.1 ohms.

(ii) Connect two of the 1m length wires in series, which double the resistance from 6.2 to 12.4 ohms.


Link?

Actually it is one single length of COILED wire. Can the answer here be related to the no. of turns in the wire?

 

[John 1234]

Ok so here goes guys... Every time a question in the Alternative to practical paper (6) in either chemistry, physics or bio pops up about improving an experiment and making it more fair, I throw away easy marks as I can't seem to identify what can be improved in the experiment. Can someone please give me a general guideline to follow or points that are usually valid in the different types of experiments that are in the syllabus. Please help coz this could actually make a difference to my grade.

 

[Vogue]

i hv the same problem as faced by John 1234. these appear as quiet straight getting marks but i never seem to find that exactly wat can be done to make the experiment more accurate?

 

[ktc]

Actually it is one single length of COILED wire. Can the answer here be related to the no. of turns in the wire?

As far as my understanding goes, the question says you can only use a 1m length of wire from the same reel to produce the consequent resistance.

Reel = a very long roll of wire, whether coiled, or stretched. It doesn’t necessarily mean a single 1m length of coiled wire, IMO.

From the reel, you can cut wires of only 1m in length, to obtain the corresponding resistance.

Since each 1m length wire you cut from the reel has a resistance of 6.2 ohms, if you cut two pieces, each 1m in length, from the reel, and connect the two wires in parallel, the total resistance decreases by half of its initial value; 3.1 ohms.

And if you connect the two pieces of 1m length wires, cut from the reel, in series, the total resistance doubles; 12.4 ohms.

This is the only rational explanation I can think of. Don’t think the question was phrased properly, so to speak. Was it a past paper question? If it was, could you provide the link here?

 

[Iridescent]

As far as my understanding goes, the question says you can only use a 1m length of wire from the same reel to produce the consequent resistance.

Reel = a very long roll of wire, whether coiled, or stretched. It doesn’t necessarily mean a single 1m length of coiled wire, IMO.

From the reel, you can cut wires of only 1m in length, to obtain the corresponding resistance.

Since each 1m length wire you cut from the reel has a resistance of 6.2 ohms, if you cut two pieces, each 1m in length, from the reel, and connect the two wires in parallel, the total resistance decreases by half of its initial value; 3.1 ohms.

And if you connect the two pieces of 1m length wires, cut from the reel, in series, the total resistance doubles; 12.4 ohms.

This is the only rational explanation I can think of. Don’t think the question was phrased properly, so to speak. Was it a past paper question? If it was, could you provide the link here?

It is a past paper question but i don't knpw which year it is. Anyways thanx. I got the answer.

 

[GetSomeLife]

A 50 cm3 sample of alcohol is mixed with 50 cm3 of water.

The volume of the mixed alcohol or water is found to be 97 cm3.
Which of the following is the best explanation?

A) Alcohol molecules fit into gaps between water molecules.
B) Some alcohol molecules evaporate.
C) Water and alcohol react to form a gas which escapes.
D) Water and alcohol react to produce a salt which then dissolves.

I would really appreciate an explanation.

 

[John 1234]

i hv the same problem as faced by John 1234. these appear as quiet straight getting marks but i never seem to find that exactly wat can be done to make the experiment more accurate?

I know right? It always seems like easy marks but I NEVER get all the marks in that question!

 

[PhyZac]

A 50 cm3 sample of alcohol is mixed with 50 cm3 of water.

The volume of the mixed alcohol or water is found to be 97 cm3.
Which of the following is the best explanation?

A) Alcohol molecules fit into gaps between water molecules.
B) Some alcohol molecules evaporate.
C) Water and alcohol react to form a gas which escapes.
D) Water and alcohol react to produce a salt which then dissolves.

I would really appreciate an explanation.

I think the Answer wud be B).... because alchol is volatile ( easily turns to gas )..
A)...Nonsense
C)...We know in fractional distillation ethanol and water ( nothing was there tht forms gas tht escape)
D)...just like above ( no salt is formed )

 

[PhyZac]

Ok so here goes guys... Every time a question in the Alternative to practical paper (6) in either chemistry, physics or bio pops up about improving an experiment and making it more fair, I throw away easy marks as I can't seem to identify what can be improved in the experiment. Can someone please give me a general guideline to follow or points that are usually valid in the different types of experiments that are in the syllabus. Please help coz this could actually make a difference to my grade.

Well in chemistry...mostly the answer wud be
*repeat and take average
*use pipette/burette instead of measuring cylinder
*use lid
For safety usually
*fume cupboard
*lab coat
*gloves...etc..!

Physicz..i need to review to tell!

 

[GetSomeLife]

I think the Answer wud be B).... because alchol is volatile ( easily turns to gas )..
A)...Nonsense
C)...We know in fractional distillation ethanol and water ( nothing was there tht forms gas tht escape)
D)...just like above ( no salt is formed )

Well, apparently, the nonsense is the right answer -__-

 

[Iridescent]

As far as my understanding goes, the question says you can only use a 1m length of wire from the same reel to produce the consequent resistance.

Reel = a very long roll of wire, whether coiled, or stretched. It doesn’t necessarily mean a single 1m length of coiled wire, IMO.

From the reel, you can cut wires of only 1m in length, to obtain the corresponding resistance.

Since each 1m length wire you cut from the reel has a resistance of 6.2 ohms, if you cut two pieces, each 1m in length, from the reel, and connect the two wires in parallel, the total resistance decreases by half of its initial value; 3.1 ohms.

And if you connect the two pieces of 1m length wires, cut from the reel, in series, the total resistance doubles; 12.4 ohms.

This is the only rational explanation I can think of. Don’t think the question was phrased properly, so to speak. Was it a past paper question? If it was, could you provide the link here?

But then the question is to complete the circuits in figures to show the lengths of wire connected in each case.
And the space provided is the same. Even if we connect in parallel in the first case, how can we fit 2 lengths (1m each) in the second case in the same amount of space provided?

 

[PhyZac]

Well, apparently, the nonsense is the right answer -__-

Assalam alikum,
Well good information.........i tried my best to get the answer!
Better luck for me nxt time...!!
Jazak Allah for correcting me !

 

[GetSomeLife]

Assalam alikum,
Well good information.........i tried my best to get the answer!
Better luck for me nxt time...!!
Jazak Allah for correcting me !

I appreciate that
Jazakallahu khairan