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data logger experimental error oscillation oscillations pendulum Resonance resonance experiment SHM Simple harmonic Motion topic 4.1 Topic 4.3 waves

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Triple A Learning IB Blogs

December 1, 2011

Simple Harmonic Motion with data loggers

Filed under: Physics — Tags: , — Andy Cockburn @ 12:41 pm

I used vernier motion sensors and a mass hanging from a spring for a lesson ao SHM this week.  It is something that I have done before but now that my school has a 1 to 1 laptop scheme and I am more familiar with logger pro I have extended the lesson further

Logger pro will record position/time, velocity time and acceleration time graphs for the oscillating spring.  Students can examine the phase difference and measure period and amplitude.  I next asked them to measure maximum velocity from their graph and compare it with calculated value from v = ωx.

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November 23, 2011

Simple Harmonic Motion

Filed under: Physics — Tags: , , — Andy Cockburn @ 12:27 pm

I just started teaching simple harmonic motion today with my grade 11 class.  Because the lesson is in the afternoon I didn’t want to go straight into the mathematical stuff.  They seem to follow that better when I teach them in the morning.  I asked them if the period of a pendulum depended on its amplitude.  Some said it did and some said it didn’t.  I then set them the task of testing their hypothesis and seeing if there is a difference within experimental error.  The lesson didn’t show very much except that their measurement techniques are not accurate.  I got them to repeat measurements to see if the difference between repeated measurements was bigger than the difference between measurements with different amplitudes.  Lets just say results were inconclusive but it was a nice intro and we did go on to define SHM, amplitude, angular velocity etc before starting the maths next lesson.

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February 10, 2011

Simple Harmonic Motion lesson 1

Filed under: Physics — Tags: , , , , — Andy Cockburn @ 10:32 am

In a recent workshop several teachers asked me if it is possible to teach SHM without using calculus.  I do.  It is very tempting to do some differentiating but unless all your students have studied calculus this will confuse them.  In my class studnets are doing different maths courses and only a few of them have studied differentiation when I teach SHM.  Most studnets find SHM one of the more challenging topics.  I think this is because they are introduced to several new equations and it is a completely new topic to them.  (something they have not met in earlier grades)

Here is my approach to teaching SHM

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Resonance

Filed under: Physics — Tags: , , , , — Andy Cockburn @ 10:23 am

This week I was teaching about resonance (topic 4.3).  I used a simple little experiment.

Hang a 5kg mass from a secure hook on about 1 or 2 m of rope.  Give the students a drinking straw and ask them to get the mass swinging by blowing.  Most will try blowing as hard as they can and very little will happen.  If they blow rhythmically at the natural frequency of vibration they can set the mass swining.

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Simple Harmonic motion Lesson 2

Filed under: Physics — Tags: , , , , — Andy Cockburn @ 10:15 am

After introducing the pricipals and equations for SHM it is important to give students practice with the many new equations they have learned.  I think students always like to solve some straightforward numerical problems to help get familiar with new concepts.  There are several equations in SHM so it is important that they have time to get a feel for the equations.  I like to tell them that the equation  v = ωxocosωt can tell them how fast a pendulum is going at a certain time and then introduce  v = +/-ω √(x02-x2) which can tell them how fast a pendulum is going at a certain position.

It is always nice to derive new equations but I dont do this for this equation.  I use a qualitative approach.  When x = 0 v will be maximum and when x = x0  which agrees with what they already know.

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