How did the physics 22 paper go?

[Quizzical Nuts]

What was the answer to how stationary waves can be formed and what role does detector plays in it ?

Aaaand, Change in momentum was ZERO right ? It rebounded with same speed so no change in momentum.

Ohhhh, I didn't get the change as zero. I got sth else :'(

 

[M.Fazy]

Ohhhh, I didn't get the change as zero. I got sth else :'(

what method did you used ? I simply thought that kinetic energy of ball was conserved making it elastic therefore surely total momentum is conserved and as the ball rebounded with same speed, i thought it will be zero. I AM NOT SURE THOUGH. So no need to be sad, tell me what method u used to figure it out ?

 

[Quizzical Nuts]

what method did you used ? I simply thought that kinetic energy of ball was conserved making it elastic therefore surely total momentum is conserved and as the ball rebounded with same speed, i thought it will be zero. I AM NOT SURE THOUGH. So no need to be sad, tell me what method u used to figure it out ?

Really? I did mv-mu to get change. I got a negative value cuz I took v as negative and u as positive. Now I feel bad. You might be right.

 

[iwillrise]

What was the answer to how stationary waves can be formed and what role does detector plays in it ?

Aaaand, Change in momentum was ZERO right ? It rebounded with same speed so no change in momentum.

For the stationary waves, I just said they're formed when the waves that rebound from the surface overlap with the waves created by the source, these waves are of the same type and in phase and all, so according the the principle of superposition, overlapped waves undergo interference to produce stationary waves. I'm not sure about all of this though.

The detector I said, in another question, was used to notice places of antinodes and nodes, so proving the presence of stationary waves..... ANYONE know the answer to this Q?

For the change in momentum, it's not zero. Bcause the ball rebounded in the opposite direction, though the speeds are the same, one will be negative, so you add them up and multiply by the mass to find change in momentum. change in momentium= m(v-u), since one of the speeds is negative, they are added up.

 

[awesomaholic101]

For the stationary waves, I just said they're formed when the waves that rebound from the surface overlap with the waves created by the source, these waves are of the same type and in phase and all, so according the the principle of superposition, overlapped waves undergo interference to produce stationary waves. I'm not sure about all of this though.

The detector I said, in another question, was used to notice places of antinodes and nodes, so proving the presence of stationary waves..... ANYONE know the answer to this Q?

For the change in momentum, it's not zero. Bcause the ball rebounded in the opposite direction, though the speeds are the same, one will be negative, so you add them up and multiply by the mass to find change in momentum. change in momentium= m(v-u), since one of the speeds is negative, they are added up.

You're right ... that's what the detector is used for ...

 

[asadalam]

What was the answer to how stationary waves can be formed and what role does detector plays in it ?

Aaaand, Change in momentum was ZERO right ? It rebounded with same speed so no change in momentum.

Stationary waves are formed when the 2 travelling waves i.e the generated wave and the reflected wave meet to form a completely destructive interference.We can detect nodes and antinodes where by moving the detector to and fro and the point where there is node will have zero deflection on detector.We can determine wavelength by measuring distance between 2 closest points that give zero deflection and multiplying by 2.
And momentum was not zero as velocity was changing as direction of movement changed.If there is no change there would be no force exerted on the walls and any container would collapse.

 

[Sahil Gupta]

will it be wrong if i wrote to measure the wavelength, measure the distance between 3 nodes?

 

[Sifat Bin Quadery]

What was the answer to how stationary waves can be formed and what role does detector plays in it ?

Aaaand, Change in momentum was ZERO right ? It rebounded with same speed so no change in momentum.

No change in momentum was -2mv.... because it was travelling in the opposite direction..... and the formula for change in momentum is final momentum minus initial momentum..... in this case final momentum is -mv and the initial momentum is mv..... hence... change= -mv-mv whic equals to -2mv.... and then u just had to put the respective values of m and v....

 

[S.Khalil]

Guys i did the biggest possible blunder....i considered that the stone got rebounded ....dont ask me why ...left that question for the end ..had to solve it in the last 5 minutes...well anyways ..my calculations according to my stupid assumptions were correct ...applied all the correct SUVAT equations...like as i thought its a rebound scenario and the object is moving upwards the acceleration must be negative....unfortunately it was not a rebound and the acceleration was positive ..so obv got the wrong answers ...applied the ___"S=ut + 1/2at^2"___ for part 1....___"v^2 -u^2=2as"__ for part 2....and displacement in the last 0.5 secs....so basically all the answers wrong due to wrong direction for acceleration....so any idea what should i expect in that question?..

 

[awesomaholic101]

Guys i did the biggest possible blunder....i considered that the stone got rebounded ....dont ask me why ...left that question for the end ..had to solve it in the last 5 minutes...well anyways ..my calculations according to my stupid assumptions were correct ...applied all the correct SUVAT equations...like as i thought its a rebound scenario and the object is moving upwards the acceleration must be negative....unfortunately it was not a rebound and the acceleration was positive ..so obv got the wrong answers ...applied the ___"S=ut + 1/2at^2"___ for part 1....___"v^2 -u^2=2as"__ for part 2....and displacement in the last 0.5 secs....so basically all the answers wrong due to wrong direction for acceleration....so any idea what should i expect in that question?..

same mistake here ... if all ur method is correct, then u will probably get marks for it ... hopefully.

 

[Abdul Hanan]

Stationary waves are formed when the 2 travelling waves i.e the generated wave and the reflected wave meet to form a completely destructive interference.We can detect nodes and antinodes where by moving the detector to and fro and the point where there is node will have zero deflection on detector.We can determine wavelength by measuring distance between 2 closest points that give zero deflection and multiplying by 2.
And momentum was not zero as velocity was changing as direction of movement changed.If there is no change there would be no force exerted on the walls and any container would collapse.

How can we measure the distance? we do not have a meter rule in the apparatus given....

 

[asadalam]

How can we measure the distance? we do not have a meter rule in the apparatus given....

This isnt like a practical where we have to describe every actual step like measure using meter rule and measure deflection is zero using protactor or stuff.In P2 we just have to outline the process.Look at 2012 June P22 Q6 b.MS just has to outline process and tell us how to utilize obtained measurements to get wavelength.There is no mention of how to measure or such.How else would we get to know the wavelength then?

 

[Abdul Hanan]

This isnt like a practical where we have to describe every actual step like measure using meter rule and measure deflection is zero using protactor or stuff.In P2 we just have to outline the process.Look at 2012 June P22 Q6 b.MS just has to outline process and tell us how to utilize obtained measurements to get wavelength.There is no mention of how to measure or such.How else would we get to know the wavelength then?

i wrote some bongi but it did said how will you measure wavelength using the ""apparatus given"", i read that a couple of times... and we didn't had a rule in apparatus... so there was no way to measure the distance between 2 points using the apparatus given... but i am not sure ... maybe yours is right.
i wrote something like find frequency in someway using the apparatus that "someway" i wrote complete bongi... and then we use known value of speed i.e 3x10^8 and put in formula v=f(lambda) to find wave length...

 

[asadalam]

i wrote some bongi but it did said how will you measure wavelength using the ""apparatus given"", i read that a couple of times... and we didn't had a rule in apparatus... so there was no way to measure the distance between 2 points using the apparatus given... but i am not sure ... maybe yours is right.
i wrote something like find frequency in someway using the apparatus that "someway" i wrote complete bongi... and then we use known value of speed i.e 3x10^8 and put in formula v=f(lambda) to find wave length...

Look at that question. It's pretty much the same thing.

 

[Abdul Hanan]

Look at that question. It's pretty much the same thing.

no in that one we can tell a way to measure the distance...
without a rule in the apparatus we cant measure distance.
lets leave it to the examiners i know i am wrong

 

[asadalam]

no in that one we can tell a way to measure the distance...
without a rule in the apparatus we cant measure distance.
lets leave it to the examiners i know i am wrong

Wohi drink C wala na ho chakr,you are looking TOO deeply into the matter
And paper ko to hafta guzr gya hai,jo hogya so hogya

 

[thementor]

If its constant acceleration, then gradeint of speed time graph is CONSTANT! meaning you can use area under graph! Why couldnt you?

How am I supposed to explain this to you.

 

[Isa Ahmed]

Please who has the question paper for the physics?

 

[Aly Emran]

How am I supposed to explain this to you.

Bang ur head on the wall
He might then figure out that there was no value given for the displacement axis of the graph

 

[Dr Death]

Bang ur head on the wall
He might then figure out that there was no value given for the displacement axis of the graph

Correct there wasn't