Physics: Post your doubts here!

[Talhakhan]

An object of mass m passes a point P with a velocity v and slides up a frictionless incline to stop at point Q, which is at a height h above P.

When a second object of mass 1/2m passes P with velocity of 1/2v, it will rise to
A-1/4h. B-1/2h.

 

[xyn1123]

A strong wind of speed 33 m s–1 blows against a wall. The density of the air is 1.2 kg m–3. The wall
has an area of 12 m2
at right angles to the wind velocity. The air has its speed reduced to zero
when it hits the wall.

What is the approximate force exerted by the air on the wall?
A 330 N B 400 N C 480 N D 16 000 N

Ans is D

 

[Jessie N.]

Good luck tomorrow!! Fight for the exam!!

 

[Dashexdan]

q18 plz

 

[Raiyan3]

Please explain why the answer to question no. 30 is C?
http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w11_qp_11.pdf

 

[Rocket1218]

Ans:

Q8 D​

16 C​

17B​

18 B​

19B​

24C​

How did you get the answer of no. 18?

​

 

[xyn1123]

From marking scheme . But I need explanation of those question

 

[Rocket1218]

From marking scheme . But I need explanation of those question

Found a formula ...
P = 0.5*ρ*A*v^3

P = power (W), ρ = density of air (kg/m^3), A = area wind passing through perpendicular to the wind (m^2), v = wind velocity (m/s)

It can be used to find the answer

 

[Muhammad TAimoor]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_s12_qp_12.pdf
MCQ 26. Please answer ASAP

 

[man1811]

HELP PLS question 8 Summer 2013 paper 1/1

 

[man1811]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s12_qp_12.pdf
MCQ 26. Please answer ASAP

Hey, i think its like this: s=v/t . Since the wave is being reflected, s =150 x 2. Then v is the speed of light, c, which is 3.0x10^8. This will give you the answer of D. I think this is how to do it

 

[Muhammad TAimoor]

Hey, i think its like this: s=v/t . Since the wave is being reflected, s =150 x 2. Then v is the speed of light, c, which is 3.0x10^8. This will give you the answer of D. I think this is how to do it

I took the speed as Speed of light, 3.0 x 10^11 and s= 300. The answer that comes, however, is wrong. Can you specify the steps?

 

[Dashexdan]

HELP PLS question 8 Summer 2013 paper 1/1

u see that train will overtake the other train when there distances will equal.
the 1st train is travelling with constant speed hence no acceleraion
the 2nd train is acclerating from rest hence no inital speed
using the formula
s=ut+0.5at^2
for the first train
s=10t
for the train starting from rest
s=0.5*0.5t^2
placing both equations equal to each other.
10t=0.5*0.5*t^2
solve nad get 40s

 

[Dashexdan]

I took the speed as Speed of light, 3.0 x 10^11 and s= 300. The answer that comes, however, is wrong. Can you specify the steps?

speed of light is 3*10^8

 

[Talhakhan]

A hose ejects the water with speed of 20m/s on the vertical wall.The cross-sectional area of the jet is 5x10^-4. If the density of the water is 1000kg/m3, find the force acting on the wall.(water comes to rest after hitting the wall)

Need help!!

 

[Muhammad TAimoor]

speed of light is 3*10^8

*Facepalm* O___O
Thanks man!

 

[Muhammad TAimoor]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_s12_qp_12.pdf
MCQ 31. How is the answer C? Won'y the field decrease as the distance increases?

 

[1357911]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_s12_qp_12.pdf
MCQ 31. How is the answer C? Won'y the field decrease as the distance increases?

The electric field strength is constant between the 2 charged metal plates.

 

[Muhammad TAimoor]

The electric field strength is constant between the 2 charged metal plates.

What about the formula E= V/D? it shows E is inversely prop to Distance b/w the plates and I've read an MCQ as well, that validates this relationship.

 

[Dashexdan]

A hose ejects the water with speed of 20m/s on the vertical wall.The cross-sectional area of the jet is 5x10^-4. If the density of the water is 1000kg/m3, find the force acting on the wall.(water comes to rest after hitting the wall)

Need help!!

what is the answer? is it 100 N or 200?

 

[1357911]

What about the formula E= V/D? it shows E is inversely prop to Distance b/w the plates and I've read an MCQ as well, that validates this relationship.

That is for when if the charge is moving from one plate to another plate.