physics 22

[Abhi Mevawala]

guyzz the speed of wave
?

 

[I don't care]

find the deceleration by 14/0.4=-35 and then distance by 2as=v2-u2 where u was 2.4ms the line was a straight line

You can't find the acceleration like that the acceleration varies with the graph and so does the force. altough it's a straight line, the v/t graph would be a curve. the area under the line was energy force plotted against distance so yea. we had to use the k.e to find the distance.

 

[Muhammad Haris Ghani]

Are you sure we were supposed to calculate using equation of motion?? I used equation of motion too to calculate ow distance... But most of the ppl calculated it by using formula work done= force x distance.. work done was there, taking force value from the graph.. and they are getting 0.081.. I think we did it wrong.. we were not supposed to calculate pa using equation of motion..

Number one cie only looks your method and your concept bro the question was given three marks it wasnt that much simple and yes let me tell you there was F as the resistive force and so the kinetic energy was not constant how then you are taking kinetic energy as constant from part 1 so its 100% correct bro

 

[Muhammad Haris Ghani]

guyzz the speed of wave
?

7.5ms

 

[Muhammad Haris Ghani]

Are you sure we were supposed to calculate using equation of motion?? I used equation of motion too to calculate ow distance... But most of the ppl calculated it by using formula work done= force x distance.. work done was there, taking force value from the graph.. and they are getting 0.081.. I think we did it wrong.. we were not supposed to calculate pa using equation of motion..

the correct answer is not 0.081 it was 0.089

 

[Muhammad Haris Ghani]

You can't find the acceleration like that the acceleration varies with the graph and so does the force. altough it's a straight line, the v/t graph would be a curve. the area under the line was energy force plotted against distance so yea. we had to use the k.e to find the distance.

Hold on the force was 14N and was constant and so the deceleration

 

[rabos1]

Number one cie only looks your method and your concept bro the question was given three marks it wasnt that much simple and yes let me tell you there was F as the resistive force and so the kinetic energy was not constant how then you are taking kinetic energy as constant from part 1 so its 100% correct bro

no, we are wrong.. quation of motion was not used.. acc was not constant..

 

[Ujjwal Basnet]

i got 120m

Mine was near that too..did we need to divide the wavelenght by 2 or wavelength itself distance?

 

[rabos1]

Hold on the force was 14N and was constant and so the deceleration

I'm telling you, we both are wrong.. you assumed force is constant.. force is directly proportional to acceleration.. if force is constant then acc would also be constant.. hence, acc value would be 9.81.. this is all wrong..

The correct method was to use work done= fxd

We only use equation of motion when object us moving in a straight line and with CONSTANT ACCELERATION..

 

[22shimmer22girly]

How
how can air resistance act on a wheel? I think the ans was weight of the wheel and the normal reaction force between the pin and the wheel.

Ofcourse it can, there was no bench or platform it was in mid-air....haha my sense of humour.....i am gonna drive the examiners completely balistic!!!!
I did so badly !!!

 

[sam1234]

Ofcourse it can, there was no bench or platform it was in mid-air....haha my sense of humour.....i am gonna drive the examiners completely balistic!!!!
I did so badly !!!

It's fine, you can nail your p1

 

[I don't care]

Hold on the force was 14N and was constant and so the deceleration

nope it wasn't constant, it was changing throughout the motion. you can only use the equations of motion when the acceleration is constant but in this case acceleration and force are not constant. so you need to use energy to calculate the distance.

 

[22shimmer22girly]

It's fine, you can nail your p1

INSHALLAH YA RAB !!!11

 

[Musab100]

45??? Impossible.. it would be in 30's...

why is 30 s ????? it was so easy paper

 

[Muhammad Haris Ghani]

I'm telling you, we both are wrong.. you assumed force is constant.. force is directly proportional to acceleration.. if force is constant then acc would also be constant.. hence, acc value would be 9.81.. this is all wrong..

The correct method was to use work done= fxd

We only use equation of motion when object us moving in a straight line and with CONSTANT ACCELERATION..

Let me tell you that you can only use w=fx when force is constant as well you can ask you teacher he would tell you the same thing no doubt come on yar try to understand

 

[Muhammad Haris Ghani]

nope it wasn't constant, it was changing throughout the motion. you can only use the equations of motion when the acceleration is constant but in this case acceleration and force are not constant. so you need to use energy to calculate the distance.

Let me make it clear to you that you can only use w=fx only when force is constant you can ask your teacher he would tell you the same thing and yes how can you use W as that kinetic energy you have found the resistive force was there which was decreasing the kinetic energy come on yar try to understand

 

[Muhammad Haris Ghani]

no, we are wrong.. quation of motion was not used.. acc was not constant..

you can not use w=fx it can only be used when force is constant also you cannot take W as that kinetic energy because that wasnt constant it was decreasing because of resistive force F

 

[rabos1]

you can not use w=fx it can only be used when force is constant also you cannot take W as that kinetic energy because that wasnt constant it was decreasing because of resistive force F

Let's just focus on paper 1 now. I have forgotten paper 2 already.

 

[Muhammad Haris Ghani]

Let's just focus on paper 1 now. I have forgotten paper 2 already.

Inshallah I m hopping for A

 

[rabos1]

you can not use w=fx it can only be used when force is constant also you cannot take W as that kinetic energy because that wasnt constant it was decreasing because of resistive force F

Let's just focus on paper 1 now. I have forgotten paper 2 already.

Inshallah I m hopping for A

Believe me or not but we did this question wrong. Ask your teacher. I hope I get an A too IA. So worried.