Before I started to see ur videos: darkness... currently... when I see ur videos: bulbs are glowing... u are a really great person!... sorry... but I just can not stop commenting about how awsome u are... :}
@@MichelvanBiezen Thanks. It was probably a very obvious question now that I think about it. But I notice textbooks never explicitly talk about this so I just wanted to be sure.
Can you please do a video about sound intensities and how that affects impedance. and how the wave changes when it goes from medium A to medium B? Thank you
Sir, first of all I want to thank you for all the knowledge you’ve given to me through out your videos without even knowing that. Second, I have a question, when light, or mechanical wave, is reflected and it changes it’s phase for 180 degrees shouldn’t the coming and reflected way cancel out? This seems logical but I know it does not happen in reality. Why is that?
Since one wave is traveling in one direction and the other wave is traveling in the opposite direction, so at some moments the waves will cancel and other moments they will add.
Michel van Biezen yes I understand that, but what about, for example, light when it reflects of a mirror, it also changes its phase for 180, but reflected light does not cancel with the coming one?
Manish, I am not sure if I understand your question correctly. With a standing wave you have nodes (that don't move) and anti-nodes where the string will vibrate up and down. Notice with the equation, the sin only depends on the position and the cosine depends on time. This equation is derived from interference of 2 waves moving in opposite directions.
I didn't understand how you simplified the y1+y2=2Asin(kx)cos(wt) Where does the cosine come from? How are those functions combined in a such way? Thanks!
Hi Michael, Incredible video's! In my text book the question for determining the displacement of standing waves is given by y(x,t) = 2Asin(kx)sin(wt). Is this the same as the equation that you derived with y(x,t) = 2Asin(kx)cos(wt)?
The best way to check it is this: When x = 0, the amplitude is always = 0. Does the equation in your book let the amplitude = 0 when x = 0? The answer is yes. Then the only difference is the time dependency. Your book's equation will have the maximum amplitude occur at a different time, so there is just a phase difference. Both equations are correct assuming a different moment in time for the starting point of the maximum amplitude. In the real world you would hold the string at maximum amplitude and let go at t = 0. Which equation would describe that situation?
Your text book is correct, however it is possible to express it both ways and both equations are correct. It makes no difference which equation you use, as they only differ in phase.
Michel van Biezen how would I know if It had a phase shift? I know for periodic motion it was Acos(wt+phi) where phi=phase shift? In other words: how would I know to use sin sin or sin cos
@@MichelvanBiezen thank you very much, could you also help me solve these two other questions? 4 How many times will the frequency of the second harmonic of a stretched string change if its length is increased by 55% and the tension decreased by 30%. 5 Two strings have fundamental frequency of 4.8 kHz and 32 Hz. Their lengths are 5.0 cm and 2.0 m, respectively. If the tension in these two strings is the same, find the ratio of the masses per unit length of the two strings.
His description of pulling and releasing the taught string at a point which is 1/2 the wave length is such a important aspect of nature we quickly forget. When we try transfer force to do work, for some reason we always forget natures favourite dance moves which sheb constantly shows us but we are too busy trying to ‘govern’ nature with our silly system of numbers. Ummm, Nature cant count to ten or perform long multiplication people. She’s a bit simple and is amply entertained by the box with the various shapes cut out of each side and the corresponding pegs that fit through the holes. She would rather just keep putting the closest peg to her in the correct correct hole over and over, while we are trying to explain that nature is actually an idiot savant who is expressing the square root of the speed of gravity, divided by the neutron flux density of a spinning white hole to 200,000 decimal places, by placing the polygon with the corresponding denomination which is calculated by.... you get the point. Nature knows how to play the f’ck outta Tetris, was born with a complete comprehension of resonant harmonics at every conceivable scale and dynamic complexity and instantaneously and instinctively understands how all the possible euclidean, hyperbolic (and unknown unknown) geometry cause/effects dynamics at immeasurable orders of magnitude, the resulting ‘equilibrium’ disturbance and the most effective method to regain equilibrium that doesn’t waste a single move in doing so. Ever..... Can’t count to 10 to save her life though let alone even recognise what a quadratic equation is even supposed to represent. And if you wanna make her laugh just tell her about how we discovered her secret dark matter she is hiding from us, her magic tricks making little balls seem to appear and/or disappear, or how we know that Gravity is the dominant force (these special ed ‘experts’ want to look up the definition of dominant... Cause it ain’t the dominant force at any testable magnitude and has never definitively been proven to be the dominant force outside our atmosphere, let alone outside our galaxy...) because we made a mathematical formula, relies on inventing and introducing catastrophic variables such as time being a physical dimension unto itself which can simultaneously run backwards and forwards and space ‘warping’ as a result of the presence of a body of mass. And don’t forget about the other fancy number puzzles that introduce absurdities like infinity and zero into the equations and led us to discovering she had irresistible holes that gobble up everything in sight apparently, including light. (But not any other EMR... And recently we have discovered/invented a white hole, what ever the fuck that is supposed to be..... If we don’t accidentally wipe ourselves out somehow by catastrophically damaging our DNA, or the Earths natural balance with its surrounding environment, then future peoples will look back in 500yrs and be like, “wow, we were a fully retarded species not 500 years ago, there must of been aliens visiting them back then cause these dipshits definitely didn’t invent things like microwave transmitters or plasma globes. How on earth they even stumbled upon AC electricity with their scientific beliefs is a mystery that still can’t be explained without ‘discovering’ aliens coexisted along side them to make the observation seem logical to our understanding.
Before I started to see ur videos: darkness...
currently... when I see ur videos: bulbs are glowing... u are a really great person!...
sorry... but I just can not stop commenting about how awsome u are... :}
that gesture you did at 6:42 is so funny lmao
sir.. you are a great teacher!!!!
YOU ARE MY LIFE SAVER THANK YOU SO MUCH
Can you explain where the extra length of string comes from when the standing wave is at its highest amplitude vs when it is a straight line.
There is some elasticity in a string, so they can stretch a bit.
@@MichelvanBiezen
Thanks.
It was probably a very obvious question now that I think about it. But I notice textbooks never explicitly talk about this so I just wanted to be sure.
It was a great question, and yes text books often do not mention these key types of nuggets of understanding.
Can you please do a video about sound intensities and how that affects impedance. and how the wave changes when it goes from medium A to medium B? Thank you
Sir, first of all I want to thank you for all the knowledge you’ve given to me through out your videos without even knowing that. Second, I have a question, when light, or mechanical wave, is reflected and it changes it’s phase for 180 degrees shouldn’t the coming and reflected way cancel out? This seems logical but I know it does not happen in reality. Why is that?
Since one wave is traveling in one direction and the other wave is traveling in the opposite direction, so at some moments the waves will cancel and other moments they will add.
Michel van Biezen yes I understand that, but what about, for example, light when it reflects of a mirror, it also changes its phase for 180, but reflected light does not cancel with the coming one?
While forming standing wave is it necessary to follow the same path can't it go downwards?
And what is the nature of graph of y=Asinkx.coswt?
Manish,
I am not sure if I understand your question correctly.
With a standing wave you have nodes (that don't move) and anti-nodes where the string will vibrate up and down.
Notice with the equation, the sin only depends on the position and the cosine depends on time.
This equation is derived from interference of 2 waves moving in opposite directions.
wao ....such a nice lctur
Sir please make video on resonance, quinck,kundt tube and also one reflection and refraction of waves.
I didn't understand how you simplified the
y1+y2=2Asin(kx)cos(wt)
Where does the cosine come from? How are those functions combined in a such way?
Thanks!
sin (A+B) = sin A * cos B + cos A * sin B
sin (A- B) = sin A* cos B - cos A * sin B
These are trigonometric identities
Hi Michael,
Incredible video's! In my text book the question for determining the displacement of standing waves is given by y(x,t) = 2Asin(kx)sin(wt). Is this the same as the equation that you derived with y(x,t) = 2Asin(kx)cos(wt)?
The best way to check it is this: When x = 0, the amplitude is always = 0. Does the equation in your book let the amplitude = 0 when x = 0? The answer is yes. Then the only difference is the time dependency. Your book's equation will have the maximum amplitude occur at a different time, so there is just a phase difference. Both equations are correct assuming a different moment in time for the starting point of the maximum amplitude. In the real world you would hold the string at maximum amplitude and let go at t = 0. Which equation would describe that situation?
That makes sense!! thank you so so much.
sir thank you so much you explained it so well you are great
My textbook says (2Asinkx)sinwt - what is the difference between yours and this one?
Your text book is correct, however it is possible to express it both ways and both equations are correct. It makes no difference which equation you use, as they only differ in phase.
Michel van Biezen how would I know if It had a phase shift? I know for periodic motion it was Acos(wt+phi) where phi=phase shift? In other words: how would I know to use sin sin or sin cos
Since sin(wt) is only dependent on time, it will depend on the position of the string at t= 0. Note that sin(0) = 0 and cos(0) = =1
Michel van Biezen ok thank you. I Appreciate all your hard work making these videos. They really help!
how can I proove that the v equation with tension over the unit mass will give us a result in m/s?
SQRT ( N/ (kg/m)) = SQRT ( kg m/sec^2 / (kg /m) = SQRT (m^2/sec^2) = m/sec
@@MichelvanBiezen thank you very much, could you also help me solve these two other questions? 4 How many times will the frequency of the second harmonic of a stretched string change if its length is increased by 55% and the tension decreased by 30%.
5 Two strings have fundamental frequency of 4.8 kHz and 32 Hz. Their lengths are 5.0 cm and 2.0 m, respectively. If the tension in these two strings is the same, find the ratio of the masses per unit length of the two strings.
I also dont understand producing the formula cause you never included that phase diference was pi....
Right?
IMYTnNERDEE2
To get further understanding you need to watch the other videos as well.
what about in the case of cosine ?
You need to use the function that matches the physical conditions and boundary conditions of the physical situation.
thanks
well explained, thanks
Amazinggggg
Thank you. Glad you liked it.
Bravo
Thank you. Glad you liked it
Excuse me? What is k, where did it come from?
k is known as the "wave number" k = 2 pi / wavelength
His description of pulling and releasing the taught string at a point which is 1/2 the wave length is such a important aspect of nature we quickly forget. When we try transfer force to do work, for some reason we always forget natures favourite dance moves which sheb constantly shows us but we are too busy trying to ‘govern’ nature with our silly system of numbers. Ummm, Nature cant count to ten or perform long multiplication people. She’s a bit simple and is amply entertained by the box with the various shapes cut out of each side and the corresponding pegs that fit through the holes. She would rather just keep putting the closest peg to her in the correct correct hole over and over, while we are trying to explain that nature is actually an idiot savant who is expressing the square root of the speed of gravity, divided by the neutron flux density of a spinning white hole to 200,000 decimal places, by placing the polygon with the corresponding denomination which is calculated by.... you get the point.
Nature knows how to play the f’ck outta Tetris, was born with a complete comprehension of resonant harmonics at every conceivable scale and dynamic complexity and instantaneously and instinctively understands how all the possible euclidean, hyperbolic (and unknown unknown) geometry cause/effects dynamics at immeasurable orders of magnitude, the resulting ‘equilibrium’ disturbance and the most effective method to regain equilibrium that doesn’t waste a single move in doing so. Ever.....
Can’t count to 10 to save her life though let alone even recognise what a quadratic equation is even supposed to represent. And if you wanna make her laugh just tell her about how we discovered her secret dark matter she is hiding from us, her magic tricks making little balls seem to appear and/or disappear, or how we know that Gravity is the dominant force (these special ed ‘experts’ want to look up the definition of dominant... Cause it ain’t the dominant force at any testable magnitude and has never definitively been proven to be the dominant force outside our atmosphere, let alone outside our galaxy...) because we made a mathematical formula, relies on inventing and introducing catastrophic variables such as time being a physical dimension unto itself which can simultaneously run backwards and forwards and space ‘warping’ as a result of the presence of a body of mass. And don’t forget about the other fancy number puzzles that introduce absurdities like infinity and zero into the equations and led us to discovering she had irresistible holes that gobble up everything in sight apparently, including light. (But not any other EMR... And recently we have discovered/invented a white hole, what ever the fuck that is supposed to be.....
If we don’t accidentally wipe ourselves out somehow by catastrophically damaging our DNA, or the Earths natural balance with its surrounding environment, then future peoples will look back in 500yrs and be like, “wow, we were a fully retarded species not 500 years ago, there must of been aliens visiting them back then cause these dipshits definitely didn’t invent things like microwave transmitters or plasma globes. How on earth they even stumbled upon AC electricity with their scientific beliefs is a mystery that still can’t be explained without ‘discovering’ aliens coexisted along side them to make the observation seem logical to our understanding.
Thanks
You're welcome!
😊
👍