# Physics: Post your doubts here!

#### funky brat

Sorry, I think my explanations were vague. Okay let me describe the thing again:

The upthrust is the weight of water displaced. The amount of water displaced has nothing to do with the density. The aomunt of water displaced depends on the volume of the cuboid. Volume is same for all the cuboids, so they will displace equal amounts of water. So they will have the same upthrust. Clear now?
YEAH THANKS REALLY.

#### farhan141

Can someone do part c please. Need it urgent.

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#### Mai(M4!)

Guys does anyone have edexcel AS physics as a pdf or active book or know where to find it ??!!

#### qwertypoiu

Can someone do part c please. Need it urgent.
Using the formula you proved above, you can find E, the Kinetic Energy required to statisfy their condition.
Next, using the relation E = VQ, you can find V. This is because the kinetic energy is being provided by the electric potential energy. You already know the charge and mass of an electron from the data provided at the beginning of paper.

#### holoholo

Paper 4 (A Level Structured Questions): The assessment of core and applications topics will be integrated. There will no longer be a section A and a section B.

What do they mean by the first statement ?

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#### funky brat

Paper 4 (A Level Structured Questions): The assessment of core and applications topics will be integrated. There will no longer be a section A and a section B.

What do they mean by the first statement ?
The applications will be merged with the questions. There will not be a separate section B for applications.

#### holoholo

The applications will be merged with the questions. There will not be a separate section B for applications.
do we have to study the As part like waves etc for A2 ?

pls pls help

#### funky brat

do we have to study the As part like waves etc for A2 ?
No this is not what it means.
You must have seen the past papers they had a section A which consisted of questions from the A2 syllabus except the applications which were in section B. Now they'll be merged together. There won't be any section B.

#### sfhn_128

someone help!!!!........
9702/s14/qp13/question 32

#### Rizwan Javed

someone help!!!!........
9702/s14/qp13/question 32

The electric field strength, E, is given by this formula:

E = F/Q (where F is force, Q is charge and E is electric field strength)

We know F = ma, so E becomes:
E = ma/q ----(i)

You're given that, K.E = k. Use the equation of K.E (1/2mv^2) to find the value of m and substitute this value of 'm' into (i)
m = 2K/v^2 ---- substituting in (i)

(i) will become:
E = ( (2K/v^2) * (a) )/ q ------(ii)

Now use the equation of motion: v^2 = u^2 + 2as
The charge starts moving from rest, so initial speed (u) is zero. And it covers a distance of 'd' for reaching plate Y, so s=d. So,
v^2 = 2ad ---- put this one into (ii)

E = ( (2K/2ad) * (a) )/ q

Simplify it, you'll get :

E = K/qd

#### farhan141

Using the formula you proved above, you can find E, the Kinetic Energy required to statisfy their condition.
Next, using the relation E = VQ, you can find V. This is because the kinetic energy is being provided by the electric potential energy. You already know the charge and mass of an electron from the data provided at the beginning of paper.
Thanks legend

#### sfhn_128

The electric field strength, E, is given by this formula:

E = F/Q (where F is force, Q is charge and E is electric field strength)

We know F = ma, so E becomes:
E = ma/q ----(i)

You're given that, K.E = k. Use the equation of K.E (1/2mv^2) to find the value of m and substitute this value of 'm' into (i)
m = 2K/v^2 ---- substituting in (i)

(i) will become:
E = ( (2K/v^2) * (a) )/ q ------(ii)

Now use the equation of motion: v^2 = u^2 + 2as
The charge starts moving from rest, so initial speed (u) is zero. And it covers a distance of 'd' for reaching plate Y, so s=d. So,
v^2 = 2ad ---- put this one into (ii)

E = ( (2K/2ad) * (a) )/ q

Simplify it, you'll get :

E = K/qd

thanks alot!

#### Bhaijan

This question is from a mock exam and I do not know its answer. I coudn't find the paper. And answer with the explanation would be appreciated.

#### Rizwan Javed

This question is from a mock exam and I do not know its answer. I coudn't find the paper. And answer with the explanation would be appreciated.
View attachment 60005
View attachment 60006
I think it's C. Because in a stationary wave, the points in adjacent loops are out phase with each other. So if the displacement of a point in one loop is S then in the adjacent loop, it should be -S.