Physics: Post your doubts here!

[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

 

[princess Anu]

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

:/ I don't think A shud be the answer...
Can u show me ur complete solution please or see mine.. tell me anything is wrong with it :s

 

[69ermalik007]

Can somebody help me with these questions?

 

[princess Anu]

Why is B wrong? Ans is D

Ahmed Aqdam

 

[waqas123]

:/ I don't think A shud be the answer...
Can u show me ur complete solution please

KE Trolley(1/2 * m * v^2) + KE Mass = Loss in GPE (mgh)
1/2 x 1.5 x v^2 + 1/2 x 0.5 x v^2 = 0.5 x 9.81 x 1.0
v^2 = 4.905

KE Trolley = 1/2 x m x v^2 = 1/2 x 1.5 x 4.905 = 3.7 J

Note: Velocity of both objects is same.

 

[princess Anu]

Oh yeahh, I was adding up their K.E's, lol -.-.
Thanks a lot

KE Trolley(1/2 * m * v^2) + KE Mass = Loss in GPE (mgh)
1/2 x 1.5 x v^2 + 1/2 x 0.5 x v^2 = 0.5 x 9.81 x 1.0
v^2 = 4.905

KE Trolley = 1/2 x m x v^2 = 1/2 x 1.5 x 4.905 = 3.7 J

Note: Velocity of both objects is same.

 

[waqas123]

View attachment 54671 Why is B wrong? Ans is D

Year?

 

[princess Anu]

Year?

J2000

 

[nehaoscar]

How to do this one??

 

[nehaoscar]

How??

 

[princess Anu]

WHY is C wrong? ?

 

[princess Anu]

View attachment 54674
How to do this one??

deltaP= change in Momentum
p= pressure

 

[nehaoscar]

Why C?

 

[nehaoscar]

View attachment 54673 WHY is C wrong? ?

Voltage would stay the same
Try using some values
eg: V = 100V and R = 10 to start with
I = 10
so pd = IR = 100 (same as supply)

Then change R = 20
I = 5
pd = 100 (still the same)

 

[Ahmed Aqdam]

View attachment 54676
How??

Resultant Moment= Clockwise moment - anticlockwise moment
4*0.4-2*0.1=1.4 N m

View attachment 54673 WHY is C wrong? ?

There is no resistance due to plates so p.d. will remain same.