Physics: Post your doubts here!

[princess Anu]

Can somebody help with any of these please:
)

 

[nehaoscar]

http://maxpapers.com/wp-content/uploads/2012/11/9702_w14_qp_13.pdf
Question number 8 - why is it A??

 

[nehaoscar]

Why D?

 

[nehaoscar]

How to do this one?

 

[nehaoscar]

How??

 

[nehaoscar]

How C?

 

[nehaoscar]

Why 2x? Because d halfes, E doubles, so x also doubles>??

 

[nehaoscar]

Thanks

but how do u know proton number decreases by 1 ? :/
idk wth is wrong wid me...i got it when i did it before but now m not

Yeah it happens always during exams that your brain just stops!
So basically it absorbs an electron right.
So an electron is negatively charged.
The nucleus has 28 protons = 28+ charge
If it absorbs one -1 charge then the charge will be 28 - 1 = 27+ charge

 

[qwertypoiu]

Can somebody help with any of these please:
)View attachment 54651View attachment 54652View attachment 54653

This should help you realise it's dcos(Θ)

As for the square wave question, I'm not sure but is it D?

There are 5 antinodes given. That represents 2 wavelengths..

2*wavelength = 293 - 14 = 279mm.
wavelength = 279mm/2 = 139.5mm = 0.1395m

f = v/wavelength = 3.0x10^8m/s / 0.1395m = 2.2GHz

 

[Mathemagical]

View attachment 54655
Why D?

Gain in Potential Energy = mgh = mgs (sin α)
Work done by engine = Fs

Efficiency = mgs (sin α)/Fs = mg (sin α)/F

 

[princess Anu]

View attachment 54660

This should help you realise it's dcos(Θ)

As for the square wave question, I'm not sure but is it D?

There are 5 antinodes given. That represents 2 wavelengths..

2*wavelength = 293 - 14 = 279mm.
wavelength = 279mm/2 = 139.5mm = 0.1395m

f = v/wavelength = 3.0x10^8m/s / 0.1395m = 2.2GHz

Thanks a lot ^.^

Btw,the ans to that ques is B ( I thought D too).. I'm attaching the screenshot of Examiner report .. see if it makes sense to you if it does then explain me too

 

[nehaoscar]

How C?

 

[nehaoscar]

Why A?

 

[princess Anu]

help please

 

[waqas123]

is it B?

It's A.
KE of Trolley + KE of Mass = Loss in GPE

 

[waqas123]

If I scored 'd' in my AS levels, and I did pretty well in paper 4 and 5 (75/100 and 27/30), then what is the maximum grade that I can score? Can I get an A?

Check the Grade thresholds of previous years. They have listed marks for every paper and grade.
You can calculate your marks in AS and then estimate the marks you need/got in Paper 4 and 5. Add them and you can get an idea of your grade.

 

[waqas123]

help pleaseView attachment 54663

Is the answer D?

Resultant force(F) = Crane Force(12000) - Weight(1000 * 9.81)
F = ma
a = F/m
a = 2190 / 1000 = 2.2

 

[princess Anu]

It's A.
KE of Trolley + KE of Mass = Loss in GPE

Which year is it.?

 

[waqas123]

Which year is it.?

I found it in a topical past papers book. The year was not written.

 

[princess Anu]

Is the answer D?

Resultant force(F) = Crane Force(12000) - Weight(1000 * 9.81)
F = ma
a = F/m
a = 2190 / 1000 = 2.2

Seems so.. I don't know the answer p