Biology; Chemistry; Physics: Post your doubts here!

[daredevil]

Question for you guys, designed by myself
A bicycle moves round a turn with a constant speed. What two statements from the following explain the force acting on the bicycle and its direction of acceleration?
1 Since the speed is constant, there is no force acting on the cycle.
2 Since the speed is constant, there is no acceleration.
3 A force acts on the cycle towards the center of the round turn.
4 Acceleration acts towards the center of the round turn.
5 Acceleration and force both act perpendicularly to each other with acceleration being tangent to the round turn and force towards the center.

A) 1 and 2
B) 3 and 5
C) 2 and 3
D) 3 and 4

is the answer B ?

 

[asd]

how ??

divide that by (25)(4200) to get 19.2 kg of water i guess :/

 

[asd]

is the answer B ?

No

 

[Talhakhan]

Need help... Question 5???
http://www.xtremepapers.com/papers/...onal O Level/Physics (5054)/5054_w04_qp_1.pdf

 

[Spidey21]

divide that by (25)(4200) to get 19.2 kg of water i guess :/

the answer to your question is D..

 

[Spidey21]

Need help... Question 5???
http://www.xtremepapers.com/papers/CIE/Cambridge International O Level/Physics (5054)/5054_w04_qp_1.pdf

the answer should b B...

 

[Talhakhan]

the answer should b B...

I also thought B but in examiner report and past paper it says about 70% students opted B ...which is wrong they say option D is correct .....
How???? Shouldn't it be B....

 

[asd]

how ??

Dude see.
For 1kg of water at 25 *C to reach 40*C, it would need = (1)(15+273)(4200) J of energy = 1209600 J
For 500g of beaker to reach 40*C, it would need = (o.5)(15+273)(5615) J of energy = 808704 J
So their total is 808704 + 1209600 = 2018304 J

So for This much energy to be given out by water which is at 60*C, it must be of this mass:
mass= 2018304/(25+273)(4200) = 0.65 kg.
PHEW!

 

[asd]

I also thought B but in examiner report and past paper it says about 70% students opted B ...which is wrong they say option D is correct .....
How???? Shouldn't it be B....

It sure is D. See the car is moving to the left, so the tyre must be moving in the opposite direction. See yourself. therefore friction must act in D.

 

[daredevil]

okay now a question from me of 30.0024 marks

Q) When a thermometer is placed into hot water, why the reading drops first then increases.

is there anyone ...?

first the glass expands so the reading drops then as the mercury starts expanding the level rises ^__^

 

[asd]

the answer to your question is D..

Hmm.. yea.

 

[Spidey21]

Hmm.. yea.

*LIKE A BOSS*

 

[Spidey21]

I also thought B but in examiner report and past paper it says about 70% students opted B ...which is wrong they say option D is correct .....
How???? Shouldn't it be B....

umm yeah m
i just thought over it and it turns out it is actually D
look the wheel is pushing the car towards the left side ( the one to which acceleration is being made) so just think when the tyre moves the tyre pushes towards the left side with the help of friction
i dont think you can understand this..:/

 

[Khadija.95]

Ummm, in the formula of heat capacity and latent heat of fusion, is mass to be taken in kg?
And how does the size of the bore affect the thermometer's sensitivity?

 

[daredevil]

i have one for reactivity series aswell
though its senseless!
POPULAR SCIENTIST CAN MAKE A ZOO IN LESS HUMID CLIMATE SATISFACTORY
POTASSIUM_SODIUM_CALCIUM_MAGNESIUM_ALUMINIUM_ZINC_IRON_LEAD_HYDROGEN_COPER_SILVER
buh it works!

I have one for the reactivity series too:
Playing Soccer Can Make All Zappy, I Love Hannah Cuz She's Gorgeous

translation: Potassium; Sodium; Calcium; Magnesium; Alluminiium; Zinc Iron lead Hydrogen Copper Silver Gold

I hope that helped

 

[asd]

Ummm, in the formula of heat capacity and latent heat of fusion, is mass to be taken in kg?
And how does the size of the bore affect the thermometer's sensitivity?

Yes in Kg. And size of the bore as in with respect to length or diameter? Well, if more length, there is more range, so less sensitivity ( range and sensitivity are inversely proportional). And if bore is thin (less diameter) the thermometer will be more sensitive.

 

[daredevil]

No

urrghh.... DARN!

 

[asd]

urrghh.... DARN!

It's D, as Spidey said. Well I'd love to see Spidey explain that too. Spidey21

 

[Khadija.95]

Yes in Kg. And size of the bore as in with respect to length or diameter? Well, if more length, there is more range, so less sensitivity ( range and sensitivity are inversely proportional). And if bore is thin (less diameter) the thermometer will be more sensitive.

Thanks

 

[Spidey21]

It's D, as Spidey said. Well I'd love to see Spidey explain that too. Spidey21

nah not now..