We also discussed ways of cooling stuff down and trying to make liquid nitrogen...
I'm away with Mr H at a physics teaching event today.
Please continue your revision for your external/internal exams.
If you have not yet used it you can try this specimen paper - questions 2,4,5,6,10,13,17,19,20,21,22,23,24,25,26 are relevant to what we have studied. The markscheme is online.
You might want to take the opportunity to do some research and find out stuff like the value of g in London and also maybe the Young modulus of copper to compare with your experimental result. You need to be able to "carry out research and report findings; sources of information are cited together with supporting planning and conclusions".
If you want to have a go at the uncertainty analysis for the Young modulus experiment then please give it a go - we will go over this next lesson.
We played 'pen races' which is a game I invented last year. I will try to make a website at some point that overlays different race tracks.
There is lots of interesting psychology research that could be done with pen races - e.g. effects of age, practice, dominant/non dominant hand, correlation with other skills, relative difficulty of different camera angles/inversions...
If you are interested in this sort of thing then talk to Miss Baker as this is her area of expertise.
Also, we did the test.
I briefly finished explaining how the choice of cladding material can reduce multipath dispersion.
We went out to the field to experience two source sound interference, and I also tried to do it with water ripples on the pond with some success. This video has a great demonstration with water ripples.
We started to make notes on two source interference, and defined coherence.
Watch this demonstration of Young's double slit experiment. You will do this experiment next lesson.
Use P196-7 (stop when you get to the "Theory of the double slit equation") and this video to make notes on the experiment.
Make sure you have a clear, labelled diagram of the experimental setup, and you are clear about the definition of the slit width and fringe separation.
PLEASE USE THE SYMBOLS AS THEY ARE IN THE TEXTBOOK - the video I linked to is good, but he uses different symbols for things, so don't use his ones.
We went over the test you did on chapter 11.
You did required practical #4 - finding the Young modulus of copper.
In particular note the new formula: W = F d cos(θ)
Also note the work done stretching a spring is HALF F x Δl
This makes sense when you consider the area under the force-displacement graph.
Answer the questions on P150. Check your answers in the back of the book and hand in on Wednesday morning before registration.
Catch up work - momentum and rockets
Please collect your HW from my locker and try to correct any mistakes before Tuesday's lesson.
Read the bottom part of P5 (from where it says 'In general') and the top part of P6 (up to where it says 'Force-time graphs') of the handout and make notes. This applies when something like a rocket ejects stuff at a constant velocity relative to the rocket, and the rocket loses mass at a constant rate.
v is the relavitve velocity that the stuff gets ejected at
Δm/Δt is the 'rate of change of mass' = i.e. how many kilograms of mass are lost per second
The first half of this video does an example calculation (he uses dm/dt instead of Δm/Δt but don't worry about that).
Print off these questions about rockets and answer them. Some of these questions are QUITE HARD, so just do what you can and don't spend ages on them.
Hand the sheet in on Monday morning before registration.
Collisions & impulse
We did a question about a collision that was inelastic, then considered what would happen if it was elastic.
Make sure you have correctly calculated t (should be around 0.4s) and the velocity it leaves the table at (should be about 2m/s). If necessary go through your calculations again.
...and also Period 4
Watch this video which I just made that should explain how to calculate the maximum possible speed from today's practical. Then consider why the actual speed was less than the maximum possible speed.
Do some indepentet work on Chapter 9. There is very little new material here so we can move quickly. Here's what you need to cover - if you have suitable notes from GCSE then there's no need to write them out again.
Then watch this video which gives an example of working through to the solution of a problem - though I would encourage you to always lay out your method is the "suvat" way for the vertical motion. There is no need to "suvat" the horizontal motion since there is no horizontal acceleration - just use velocity = displacement/time for the horizontal part.
Use P126-7 and these videos to make notes on horizontal projection.
Now answer the questions on P127 and check your answers in the back of the book.
Answer Q1-4 on P130 and bring to next lesson.
Measuring g by free-fall
We did a practical to measure g by free-fall.
You recorded this in your lab books.
Finish your practical write-up. Make sure you have:
put the date on each page of your work
calculated the gradient
worked out g based on your gradient
included a diagram of the apparatus, showing the height you measured
Also write a sentence or two that concludes & evaluates your experiment. What did you find, how does it compare to the expected value, and what reasons could there be for any discrepancy between your measurement and the expected value of g.
Acceleration due to gravity
We estimated g by timing a ball falling over a known distance.
We considered the impact of increasing and decreasing the height on the quality of the measurement.
We looked at percentage uncertainty.
You read P119-120 and answered the questions on P121. Check your answers in the back of the book
Make notes on projectile motion. Use P126-7 and this video.
Next lesson you will find g by experiment (using a more sophisticated method that I demonstrated today) and we will start doing some projectile motion problems.
I showed you how to solve suvat problems, and we did a few examples.
We did a practical to investigate the acceleration of a marble rolling down a ramp at different angles.
I marked your answers to the questions on P110-111 and gave out the markscheme.
Correct your answers to P110-111, using the markscheme where necessary.
Finish your graph.
Next lesson we will move onto suvat problems with vertical motion, which can be harder.
Watch this video to see how a harder question is approached, and see how important it is to be careful with the sign (+ or -) uf your numbers.
In physics we will almost always consider upwards to be positive.
Cover Lesson - Independent Work
The classwork is to recap on stuff we did on moments.
Answer Q4-8 on P108-109, drawing diagrams for each question and making your working clear. Check your answers in the back of the book.
Answer Q2-4 on P110-111. You will need a bit of graph paper for Q2. The answers to these are not in the back of the book - we will go through them next lesson.
You should be familiar with the formula a = (v-u)/t from GCSE. Answer Q1-4 on P115, which use this formula, and check your answers in the back of the book.
Bring all this to tomorrow's lesson - I won't be able to mark any of it before the lesson.
Graphs of Motion
We went through the HW, and some subtle points about stability and the force needed to tilt something.
We did a moments question that invovled working out the perpendicular distance.
We recapped in detail on graphs of motion - if you missed the lesson then you really need to go over this before next lesson.
The "suvat" equations are a set of equations that can be used to solve problems when an object is accelerating uniformly.
Watch this video and read P116-8 to find out what the suvat equations are, and how they are derived.
You don't need to be able to derive them, but it's very nice to see how they can be found by looking at graphs and using your existing knowledge.
Bring your notes to next lesson, when we will start to use the suvat equations to solve problems.