Watch this video which shows you the pattern produced by a laser passing through a diffraction grating. Notice how sharp the fringes are, and how widely spaced they are.
Answer Q1 and Q3 on P207 and check your answers in the back of the book.
Bring your work to next lesson.
Two source interference
Classwork
We went through the notes you made on two source interference.
We saw the fringe pattern produced by a double slit illuminated with a red laser, and what happened when one of the slits was covered. Here is a photo I took of the double slit demonstration last year:
We started to do some questions on P198 and went through Q1 - please check your answers to the others in the back of the book.
We discussed the origin of the single slit interference pattern, but the explanation for it is not on the syllabus. We also started to discuss the shite light diffraction pattern - you can add to this with your HW.
Homework
Read P200-201 and add to your notes where recessary - we have covered most of this but you might want to add more.
Answer Q1 and Q3 on P201.
Read P202-204 and make notes, especisally on the formula for single slit diffraction fringes. The derivation is not on the syllabus.
Answer Q1-2 on P204.
Hand in your answers to the questions before Thursday morning.
Don't worry about the derivation on P198 at this stage.
Total internal reflection
Classwork
We went through the graph from last lesson.
We did another refraction practical to investigate total internal reflection.
We made notes on optical fibres and multipath dispersion.
Homework
Read P193-4 and add to your notes from the lesson - in particular about crossover of information between fibres, and endoscopes. You need to know about coherent bundles.
Answer Q1 and 2 on P208. Leave out Q1 b ii). Bring your answers to next lesson.
We derived the formula for the critical angle, and recapped on what refractive index is.
We did a practical to investigate refraction.
Homework
Complete your graph and calculate the gradient.
Read P193-194 and answer Q1-3 on P195 and hand in on Monday morning when we get back.
Have a good half term.
Past Paper Questions
Classwork
We went through the homework and discussed Huygens' Wavelets - you can google this if you want to read more about it. It's good.
Note:here's a video about Huygens' Principle which is very similar to what I said in the lesson. Except the guy sounds more excited about it than me...
We made some brief notes on key terms like strength, stiffness, brittle, ductile, plastic, elastic etc.
We looked at Searle's apparatus for measuring Young's Modulus (see P168).
We examined the stress-strain curve for steel in detail (see P168).
Also I just found this video which is really good - it shows a real stress-strain curve using the method I described in the lesson. If we have time we can watch it next lesson.
Homework
Answer the past paper questions and hand in on Thursday morning before registration.
Stress-strain curves
Classwork
We explored the concept of strain with a few examples, and introduced stress-strain curves.
We have still not really discussed Young's Modulus, but it's not too tricky and hopefully you've got the idea from the textbook and the video from last lesson. Will discuss next lesson.
Homework
Answer Q3-4 on P169 and Q1-2 on P171 and hand in on Monday morning.
Stress
Classwork
I gave some feedback on graphs and calculations - a common error was to mistakenly give the energy in joules without converting cm to m.
We made some notes on stress and measured the breaking stress of copper.
Answer Q1-2 on P169 and hand in on Thursday morning.
Springs, combinations and energy
Classwork
We collected data for the extension of an elastic band an a spring when loading and unloading.
We made some notes on springs, combinations of springs in series and parallel, and the work done extending a spring/elastic band.
We saw the origin of the formula W.D. = ½FΔL and derived the formula W.D. = ½k(ΔL)² for springs where Hooke's law applies.
These formulae only apply when the force and extension are directly proportional - otherwise you have to work out the area under the graph somehow.
Homework
Plot a graph of your loading and unloading data, and calculate the work done loading up to makimum load, and the energy recovered as the load is released.
If one person in each pair does one of the graphs, then I will photocopy them for you.
Hand in on Monday morning.
Springs
Classwork
I gave you some feedback on the recent test - please go through and complete your corrections.
We did this experiment to determine the spring constant of a spring and combinations of springs in series and parallel.
Homework
Please plot a graph of your results that will enable you to calculate the spring constant. Plot all your graphs on the same axes.
Complete the sheet and bring both to next lesson.
Measuring Density & Calculating Uncertainty
Classwork
We measured the density of an aluminium cylinder and calculated the percentage undertainty in this measurement.
Also, since there are so many of you interested in engineering it might be a nice idea to do an engineering-based trip during the "bridge to A2" after your AS exams. If you have any ideas of somewhere we could go to visit for a day then let me know and I'll see what I can do...
We answered the questions on P150 - please catch up on this if you missed it.
We considered the energy transfers in a pendulum (see also P152).
Homework
Do some reading and answer Q1-2 on P152, Q1-2 on P154, and Q1-2 on P156.
Hand these in any time on Monday.
Friction
Classwork
We went though parts of the homework and discussed the idea of 'g-force' and the equivalence of gravity and acceleration.
We did an investigation into how the mass of a block resting on a table affects the friction bewteen the block and the table.
Homework
Make notes on work and energy - particularly how to calculate work done when the force and the displacement are in different directions, and the use of force-displacement graphs.
Use P148-150 of the textbook and watch the first five minutes of this video (the second half is not so important).
Actually this video might be better than the one I linked to above, since it covers graphs too.
We will then do some questions on this next lesson.
Car Safety
Classwork
We went through the HW.
We built and tested crumple zones - if I get a minute I'll put the videos on YouTube and Yammer.
We held a coin that Isaac Newton himself may have held. It was amazing.
Homework
Imagine the kid from the worksheet rolls a train (mass 50g) down a slope with an angle of 10° and the train accelerates at 0.2ms-2. Draw a diagram and calculate the frictional force on the train.
Read P140-142 and make notes (you have done lots of this at GCSE). Answer Q1-3 and hand in on Thursday morning with your answer to the train question too.
Terminal Speed, Free Body Diagrams
Classwork
We watched your videos about terminal speed - I was v impressed and they all had really good aspects to them.
We did Q1-2 on P139.
Homework
Read and make notes on P135-7.
Watch this video which should help with pulley problems (see P137).
Watch this video which should help with trailer problems (see P135). NOTE: this guy makes a mistake about Newton's Third Law (!!!) can you spot it and correct it?
Answer Q1-3 on P137. Hand in on Monday morning before registration. Draw clear diagrams where necessary.
Newton's Laws
Classwork
We did some basic calculations involving mass, weight and the formula W = mg.
We went through a couple of questions from the test at the end of last half term.
We introduced Newton's three laws, although we have not done any example problems yet.
We drew some free body diagrams - more on this next lesson.
Homework
You need to know about terminal speed. You have done this before so I don't want to spend ages teaching it again.
Brush up on terminal speed (see P138-9) and produce a short video (absolute max 5 minutes) and upload it to Yammer so we can watch it next lesson.
You can work on your own or in groups. You can borrow the slow motion camera if you like.
Test
Classwork
We did the test.
Homework
Go through your test and correct. I'll put the markscheme on here soon and maybe make a video about one of the questions. Here's the markscheme.
Projectile Motion + Recap
Classwork
We did Q5-7 on P130-131.
Homework
Revise for test on Friday.
Here are the markschemes for the past paper questions in the textbook for Chapter 7 and Chapter 8.
Projectile Motion
Classwork
We worked though a few examples of projectile motion.
We did a practical to find the speed of a ball rolling off a table.
REMINDER FOR NEXT LESSON: discuss the practical in terms of random and systematic errors.
Homework
Answer Q1-3 on P127 and hand in on Tuesday morning before registration.
For Q2 part c it is asking what the velocity is just as it hits the sea. You have to combine the horizontal velocity and the vertical velocity, remembering that these are both vectors.
more suvat
Classwork
We went through an example of a two stage suvat problem (sand bag being dropped then coming to a stop when it hit floor)
Finish the graph and deduce the acceleration. Bring to next lesson.
Read P126-7 and watch this video which introduces projectile motion. Make notes on these.
Watch this video (link starts at 50s - you can ignore the first bit) which is a great demonstration of the difference between the horizontal and vertical motion of a projectile.
We will then use these ideas to solve projectile questions next lesson.
suvat
Classwork
We discussed when the suvat equations can and can't be used.
We did lots of examples of suvat problems (including Q1+3 on P121).
We thought about getting numerical information from words in the question, e.g. 'an object accelerates from rest...' tells you that u=0.
We demonstrated that objects fall at the same rate (assuming air resistance is negligible). For a more lengthy discussion see this video.
Homework
Q1-3 P125 - hand in Monday morning before registration.
The "suvat equations" are a set of 5 equations which help us solve problems about something that is moving with constant acceleration.
s = displacement, u = initial velocity, v = final velocity, a = acceleration, and t = time.
Watch (and optionally make notes on) this video which derives the suvat equations, using P116-8 of the textbook for help.
You do not need to be able to derive the suvat equations, or even remember them (they are on the formula sheet) but it is not too difficult and it does help your understanding.
Have a look at this example here which shows you how to solve problems using suvat equations. There are plenty more suvat examples on YouTube - e.g. here.
Then try to answer Q1-2 on P118, and hand these in on Thursday morning before registration.
Graphs of motion
Classwork
We went through the homework, then did some detailed recap work on graphs of distance, displacement, speed and velocity.
Homework
Answer Q2-4 on P130 and hand in on Monday before reg.
We worked through an example of an object in equilibrium on a slope, and resolved the weight of the object into components parallel and perpendicular to the slope.
We did a brief recap on moments (this was v quick since you covered a lot at GCSE).
We did a practical to find the weight of an object and a metre ruler using moments.
We then used components to help us add together two vectors that were not perpendicular to each other.
Finally we looked at situations where three forces acted on an object in equilibrium, and resolved into components to find an unknown force - more on this next lesson with a practical activity.
Homework
Answer P.93 Q.3-4 and P.96 Q.1. Hand in tomorrow morning.
Textbook Reference
P92 and P94-6 of AQA and P14 of AP4U
Scalars and Vectors
Classwork
Quick overview of course, then we started looking at scalars and vectors (which you covered at GCSE).
This video gives an excellent overview of scalars and vectors - it may seem a bit slow-moving but I recommend it highly.
This video shows you how to add two non-parallel vectors - again it is quite slow but it is good. If you want to skip straight to the parallelogram method (which is on the AQA syllaubs) go here.
This video shows you how to add two perpendicular vectors using Pythagoras' theorem.
Homework
You should all watch the first video on scalars and vectors, and add to your notes where necessary.
If you want to make further notes on the parallelogram method or on basic use of Pythagoras and trigonometry, please use the videos above.
