SHM Practicals

The AH today were working in 3 groups to research via practicals and notes about SHM. The task is given below. Well done to Morford and Hodgson who created the following from their practical, with very little assistance. Their results were so good I thought I’d share them.

Mr Morford wrote
“These graphs are from our recent experiment to determine the effect of damping on an oscillating mass. A mass was hung from a spring over an Alba Ranger ultrasound device. We then analysed our measurements using excel and graphed our results to find the decay due to damping.”

Morford & Hodgson (2019)
Check out the great phase lag and the obvious proof of SHM showing a is proportional to -ky
The period isn’t constant because the spring started moving with horizontal motion but the amplitude certainly deteriorated
I’ll need to check this….but it looks good!

This was the task for the class and my thanks to the IoP for their Practical Physics lessons and to the other places referenced for some great practical techniques. I will neaten this post later, but I promised Morford and Hodgson that I would post tonight!

Hopefully I can collate the rest of the groups information soon.

By the end of the lesson you should……

  • You to have the spring constant for two of the springs by two different methods.
  • A graph of d v t, v v t, and a v t
  • A value of the period of spring for various masses
  • Discovered the effect of amplitude on the period Found the effect of damping (so find out what that is)

https://www.webassign.net/question_assets/ncsucalcphysmechl3/lab_7_1/manual.html

http://www.dartmouth.edu/~physics/labs/descriptions/spring.mass.oscillator/spring.mass.oscillator.writeup.pdf

https://www.birmingham.ac.uk/undergraduate/preparing-for-university/stem/Physics/stem-legacy-SHM.aspx

https://www.cyberphysics.co.uk/topics/shm/springs.htm

http://practicalphysics.org/investigating-mass-spring-oscillator.html

Investigating a mass-on-spring oscillator

Demonstration

A mass suspended on a spring will oscillate after being displaced. The period of oscillation is affected by the amount of mass and the stiffness of the spring. This experiment allows the period, displacement, velocity and acceleration to be investigated by datalogging the output from a motion sensor. It is an example of simple harmonic motion.


Analysis 
Measurement of period 
Period and Amplitude Observe that the period appears to be independent of amplitude. 
 
Effect of mass 
A straight line is the usual result, showing that the period squared is proportional to the mass. 
 
Velocity and acceleration 
A plot of the resulting data shows a ‘velocity vs. time’ graph. Note that the new graph is also sinusoidal. However, compared with the ‘distance vs. time’ graph, there is a phase difference – the velocity is a maximum when the displacement is zero, and vice versa. 
 
A similar gradient calculation based on the ‘velocity vs. time’ graph yields an ‘acceleration vs. time’ graph. Comparing this with the original ‘distance vs. time’ graph shows a phase difference of 180°. This indicates that the acceleration is always opposite in direction to the displacement. Teaching notes

Aim 
To find the force constant of a helical spring by plotting a graph between load and extension.

Aim: To find the effect of damping on an oscillating spring

Aim: To find the effect of mass on an oscillating spring

Aim: To use the formula for an oscillating spring to find m or k etc

Damping Practicals

Using Tracker to Discuss Damping

Great teamwork this week, with teachers, technicians and students all getting some great results using tracker.

We wanted to see if we could get some damping examples.

We took a pendulum that was just over a metre long and set it in motion over a blue tray. We filmed the pendulum and uploaded this into tracker. Part of a metre stick was used for calibration purposes.

Theo has analysed this to try to show that the amplitude remains constant, if there is no damping. The graph does seem to shift a little towards the positive direction and we are having some good ideas as to why, such as camera slide and swinging forward and back rather than side to side,  but it was probably due to the blurred film.

We then poured water into the tray and repeated the experiment pulling the pendulum back to the same point. Angus produced the tracker trace below. This is pretty blurred and distorted due to the refraction by the water.

Daniel had a clearer film to analyse and got a great plot of displacement with time to show how the amplitude decays with time.

If you can afford the top of the range camera, unlike the teacher, you can get a lovely plot, even if the pendulum appears to be hanging upside down!

You can clearly see that the amplitude decreases. Calculating the period, peaks arrive at the following times

Time (s)
2.23
4.67
7.07
9.53
11.9
14.4
16.8
19.3

This gives a period of approx. 2.4-2.5 seconds.

Quanta & Waves Resources

Below are some accumulated resources. Thanks to all of those who produced them.

ah-quanta-summary notes problems-2015 Thanks to RGC for these notes

quanta-and-waves-student-booklet-i-ror Thanks to Mr Orr for these.

Quanta and Waves Student booklet I ROR pdf version of the above

4.2 Energy changes during simple harmonic motion

ah waves summary notes and problems 2013 RGC notes thanks for these

PhysicsQuantaandWaves_tcm4-726389 Andrew McGuigan Numerical Questions

ah quanta summary notes and problems 2015 LA

ah quanta tutorial solutions 2015

ah uncertainties experiments 2013

ah waves summary notes and problems 2013

ah waves tutorial solutions 2013

Quanta

glossary-of-terms-table2

stellar  physics pdf       stellar physics.doc

Properties_of_stars_and_stellar_evolution

electrons-exhibit-both-wave

cosmic-rays A quick research task on cosmic rays.

cosmic-rays-answers The answers to the sheet above.

solar-wind-magnetosphere

solar-wind-magnetosphere-answers

Scientist think that the Earth is due a “Magnetic Flip” Research this starting at the link below and then answer the AH Revised question on this from the 2015 Paper Q11

Here is a Radio 4 programme talking about the consequences of a polar flip. If you want to view further programmes click on the link below.

http://www.bbc.co.uk/curious case of Rutherford and Fry

 

https://www.physics.org/facts/frog-magnetic-field.asp

soho_fact_sheet

The number of sunspots is an indication of solar activity. Research this and then complete the AH Revised 2013 paper Q6.

quantum-mechanics

unit-2-part-1-quanta-notes

 

Quantum Tunnelling – strange but true

Background

What is the Uncertainty Principle? Minute Physics

https://www.youtube.com/watch?v=7vc-Uvp3vwg

Quantum Tunnelling is the process by which a particle gets across a barrier that it cannot classically pass.

It is related to wave-particle duality in that it is a result of the wave nature of a particle.

The probability of the particles getting through the barrier drops exponentially with the thickness of the barrier.

“>What is Quantum Tunnelling? Minute Physics

https://www.youtube.com/watch?v=cTodS8hkSDg

How to walk through walls- Quantum Tunnelling

https://www.youtube.com/watch?v=c6bn_tPDb1M

Is Quantum Tunnelling faster than the speed of light?

https://www.youtube.com/watch?v=-IfmgyXs7z8

Quantum Entanglement

https://www.youtube.com/watch?v=tafGL02EUOA

 

 

Waves

shm-intro

unit-2-part-2-waves-notes

shm INTRO

PhysicsQuantaandWaves_tcm4-726389

Tutorial AH Revised Booklet v2

AH (SHM)

Signature


 

Quantum Mechanics

  • I think I can safely say that nobody understands quantum mechanics.

But here is a great video to help you understand what is happening

Quantum Theory Full Documentary

https://youtu.be/CBrsWPCp_rs?t=207 this link is set up so you miss the blurb at the beginning.

Here is a link to brief notes on the important discoveries leading to the Quantum Mechanics ideas we know today.

The Sectrets of Quantum Physics

  • We have always had a great deal of difficulty understanding the world view that quantum mechanics represents. At least I do, because I’m an old enough man that I haven’t got to the point that this stuff is obvious to me. Okay, I still get nervous with it…. You know how it always is, every new idea, it takes a generation or two until it becomes obvious that there’s no real problem. I cannot define the real problem, therefore I suspect there’s no real problem, but I’m not sure there’s no real problem.
    • Richard Feynman, in Simulating Physics with Computers appearing in International Journal of Theoretical Physics (1982) p. 471.
  • We choose to examine a phenomenon [Double-slit experiment] which is impossible, absolutely impossible, to explain in any classical way, and which has in it the heart of quantum mechanics. In reality, it contains the only mystery. We cannot make the mystery go away by “explaining” how it works. We will just tell you how it works. In telling you how it works we will have told you about the basic peculiarities of all quantum mechanics.
    • Richard Feynman, The Feynman Lectures on Physics: Commemorative Issue, Vol. 3 Quantum Mechanics (1989) 1-1, “Quantum Behavior.”