Biology; Chemistry; Physics: Post your doubts here!

[Tuba noor]

ALLAH is there , who help us
INSHA ALLAH paper will be very good

 

[Mahnoorfatima]

Well look each of our eyes looks at something different. It is the brain that collects the image from both eyes and then creates an overall image. Thus if light falls on the blind spot of one eye, it won't fall on hte blind spot of the other eye. Thus one eye will view something. The brain then fills the gap

Oh right. Thank you!

 

[Enferno]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_s13_qp_41.pdf

Can someone please explain.. Question 1 part a(ii), (iii), f... and 3(c).

a)i) Because the difference is very less between the values i.e all are near to 1 second. So to actually see the difference between the values, we need to measure it to 2 dp. Else, all the values will be same i.e 1 second.
f) heavier so the air resistance has same effect on both hence same values

 

[Laibaaa]

Guys can someone please explain Youghurt making and Cheese making to me? :/ pleasepleaseplease. And the enzymes involved pleaseee.

 

[Fate0]

Guys can someone please explain Youghurt making and Cheese making to me? :/ pleasepleaseplease. And the enzymes involved pleaseee.

Yoghurt.
Heat milk to 90 then cool to 40.
Add bacterial culture. Lactobacillus and Streptococcus.
The bactera create an anaerobic condition and convert lactose, milk sugar into lactic acid.
Lactic acid curdes milk protein, caesin.
This forms the texture of the yoghurt. Flavouring may be added.

In cheese you add all the same to milk but you add rennet aswell.
Rennet clumps with caesin in presence of lactic acid and forms curds.
This is known as curdling. The curds are separated by draining the whey(liquid).
The curds are pressed in moulds and cheese is left to ripen.

 

[***amd***]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_s13_qp_41.pdf

Can someone please explain.. Question 1 part a(ii), (iii), f... and 3(c).

Q3 (c)

 

[Enferno]

View attachment 41299
Q3 (c)

Thats not correct, check marking scheme

 

[Fate0]

View attachment 41299
Q3 (c)

Um shouldnt the curve start from above 0, considering there's the initial temperature?

 

[funky brat]

What's wrong?

That pattlier or whatever.

 

[***amd***]

Um shouldnt the curve start from above 0, considering there's the initial temperature?

we have to record the temperature of the sensor, not the oil. so initially where it was we dont know. Zero will be ok to be used as the initial temperature here. u may use some other value if you want.

Um shouldnt the curve start from above 0, considering there's the initial temperature?

yeah, whats written there?

 

[kirann]

Hmm. Every reflex action does. But the knee jerk does not.

no, involuntary actions does not include sensory neurones.

 

[Uchiha-Sasuke]

View attachment 41299
Q3 (c)

Temp sensor is in contact with oil .. oil has initial temp (we don't know) data logger should should temp increase as the second student REPEATS the experiment as stated .. we must assume that oil is being heated, again ..

 

[***amd***]

Temp sensor is in contact with oil .. oil has initial temp (we don't know) data logger should should temp increase as the second student REPEATS the experiment as stated .. we must assume that oil is being heated, again ..

View attachment 41312

lets leave this for tomorrow

 

[Uchiha-Sasuke]

Can I get a drawn Q1 a)

 

[Awesome12]

lets leave this for tomorrow

This is the ans

we have heated it for 15 minutes only. Which implies it is then cooling, but 5 minutes is not adequate for it to reach room temp

 

[Dark Destination]

This is the ans
View attachment 41319
we have heated it for 15 minutes only. Which implies it is then cooling, but 5 minutes is not adequate for it to reach room temp

But who said the temperature would reach 90 in 15 minutes?
They just said heated for 15 minutes, so the temperature can be anything, higher than room temperature.

And why should the line from 0 to 15 be with a decreasing gradient? Why not straight line?

 

[Ram97]

Physics ATP
Best way to determine the accurate/precise time for one oscillation of a pendulum???

 

[funky brat]

Okay final question.
Why are the celeary stalks curved when they are cut length wise with a blade? Anyone?

 

[kirann]

how to prepare home-made yoghurt?

 

[funky brat]

Guys leave Physics for tomorrow. -__-