Physics: Post your doubts here!

[Jacob Park]

What's the answer? Is it 19ms?
I thnk there is missing information

Nah, that's all information I got.

19 is correct, how did you figure it out?

P.S Dont worry i got the answer.

 

[Jinosupreme]

Anybody know? Answer is B, why isnt half life 90 minutes?

 

[Jinosupreme]

Anybody know? Answer is B, why isnt half life 90 minutes?

 

[WYuMon]

Nah, that's all information I got.
u=28 a=-9.81 v=? s=22
a is negative because the car is going up, its going against the gravity and we know gravity always acts downward
v^2=u^2+2as
v^2=28^2+(2x-9.81x22)
v=18.8
Then round off, therefore v=19
19 is correct, how did you figure it out?

P.S Dont worry i got the answer.

 

[WYuMon]

Anybody know? Answer is B, why isnt half life 90 minutes?

Easy, it indeed took 90mins for the 1st half life
But you will need more info about its 2nd half life
The 2nd half life and the 1st should be the same value
The information is not in the table
Therefore, you can't be sure if the half life is 90mins or something else
It took 90mins for 424counts to drop to 212
But no information given how long it took for 212 to drop to 106
So its Uncertain

 

[Jacob Park]

10 The diagram shows a barrel suspended from a frictionless pulley on a building. The rope
supporting the barrel goes over the pulley and is secured to a stake at the bottom of the building.

A man stands close to the stake. The bottom of the barrel is 18 m above the man’s head. The
mass of the barrel is 120 kg and the mass of the man is 80 kg.
The man keeps hold of the rope after untying it from the stake and is lifted upwards as the barrel
falls.
What is the man’s upward speed when his head is level with the bottom of the barrel? (Use
g = 10 m s–2.)
A 6 m s–1 B 8 m s–1 C 13 m s–1 D 19 m s–1

Could you guys help me to solve it out !

 

[Jacob Park]

10 The diagram shows a barrel suspended from a frictionless pulley on a building. The rope
supporting the barrel goes over the pulley and is secured to a stake at the bottom of the building.

A man stands close to the stake. The bottom of the barrel is 18 m above the man’s head. The
mass of the barrel is 120 kg and the mass of the man is 80 kg.
The man keeps hold of the rope after untying it from the stake and is lifted upwards as the barrel
falls.
What is the man’s upward speed when his head is level with the bottom of the barrel? (Use
g = 10 m s–2.)
A 6 m s–1 B 8 m s–1 C 13 m s–1 D 19 m s–1

Could you guys help me to solve it out !

 

[WYuMon]

Is it C? 13?

 

[Jacob Park]

Is it C? 13?

Nope, the answer is A, 6

 

[WYuMon]

Ahh then I don't know:-(

 

[snowbrood]

View attachment 32886
Jacob Park

 

[Musab100]

can anyone help me

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w12_qp_12.pdf

MCQs :
2
16
17
18
27
30
34
36
38

 

[Afza Munir]

give me 10 formulae with base units...!!!!!!!!

 

[♫Prince Shah♫]

i want the formulas of as level physics!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
If any1 have it please help me!

 

[TheStallion-Reborn]

can someone provide the notes that may help me understand the chapter "units" in a better way?

XPC?? danial 234

 

[danial 234]

XPC?? danial 234

Saad Mughal can help you in this. cz i m not very good at physics. srry.

 

[shikha95]

Has anyone else noticed that in all pV=nRT, when converting from cm^3 to dm^3 , they multiply it to 10^-6 and not 10^-3. Can someone please explain that? ASAP! Thanks!

 

[Jinosupreme]

Has anyone else noticed that in all pV=nRT, when converting from cm^3 to dm^3 , they multiply it to 10^-6 and not 10^-3. Can someone please explain that? ASAP! Thanks!

It's not from cm^3 to dm^3. It is from cm^-3 to m^3, cause u are converting to SI unit, that's why is m^3.

 

[shikha95]

It's not from cm^3 to dm^3. It is from cm^-3 to m^3, cause u are converting to SI unit, that's why is m^3.

Thanks!!!

 

[shikha95]

It's not from cm^3 to dm^3. It is from cm^-3 to m^3, cause u are converting to SI unit, that's why is m^3.

Thanks!!!

 

[snowbrood]

can anyone help me

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w12_qp_12.pdf

MCQs :
2
16
17
18
27
30
34
36
38

for question no 16
there are three forces acting on an object as it is lowered in an liquid. gravitational pull(downwards) upthrust(upwards) and viscous drag(upwards)
upthrust is the difference between the (pressure acting on the top of object)- (pressure acing on the bottom)
Viscous drag is the force that a solid experiences as it is lowered down the object due to its viscosity or density( we rather like to say viscosity when referred to a liquid).
since the object is stationary so no viscous drag. gravitional pull equals upthrust.

for q 17
C is the correct answers as
clockwise moment=anti clockwisemoment
(14*5)=(2*5)+(4*15). take the moment from pivot.

for q 18
2.1*9.81/cos65

for q27
young modulus = stress/strain
since we want ratio of x to y so lets consider x
2*youngmodulus =2*stress
area=pi*d^2/4
we have 2d in case of x so
area=pi*(0.5d)^2/4
area=(pi*d/16
this area is 1/4 of the area as in y

stress=force/area
2*stress=force/area*0.25
force=2*0.25=0.5
0.5:1