If you are not sure about some of the questions, check these answers.
You did a practical to investigate moments for a balanced see-saw, and some of you foudn the weight of an object using moments calculations.
We discussed people's explanations of how the crushing can demonstration worked.
I demonstrated a pair of Magdeburg Hemispheres and we discussed why they are hard to pull apart, and why larger hemispheres would be even harder.
I then introduced the concept of moments, and you made notes on moments, including the formula and some examples.
Complete the sheet I gave out and hand in before registration on Wednesday morning.
Optionally, you could look up some videos of crushing stuff using a hydraulic press (e.g. a bowling ball) - later this year you will learn how hydraulic presses work.
DO NOT try to build your own hydraulic press at home......
I gave you some feedback on the HW and we considered why there are so many different units for pressure.
We did some recap on the particle model for solids, liquids and gases. If you missed the lesson, watch this video.
At great length, I demonstrated crushing a can using two methods. One method was to suck the air out with a vacuum pump. The other method was to boil water in the can so the air was pushed out, then seal it and let it cool. As the water vapour inside condensed, the can was crushed.
Here is a video of a larger scale version of method 2.
We started to make notes on the crushing can demo.
I want you to complete your notes on the demonstration, and explain why the can was crushed using method 1.
Please make sure you include diagrams and an explanation of what the particles inside and outside the can are doing.
Please hand in before the end of the week. (I said bring to next lesson, but have changed my mind.)
This video will help with the particle explanation.
This video shows another demonstration that should help you understand what's going on. I will show you this demonstration next lesson.
Pressure in Fluids
We went over the HW and common mistakes.
We looked at some things that are designed to exert high or low pressure, and did some calculations. Examples were snowshoes, caterpillar tracks, and drill bits.
I showed you a demonstration like this one which shows that the pressure in a fluid increases with depth.
We made notes on pressure in fluids, including the fact that the shape of the container does not affect the pressure - only the depth.
I taught you about standard form (you will do this in maths at some point).
We went over the test you did on sound.
You started to calculate the pressure you exert on the floor.
You have measured your weight in newtons.
Find the area of one of your feet, then work out the total area in contact with the floor when you are standing up.
Calculate the pressure you exert on the floor.
Do all this on a single sheet of graph paper, and hand in tomorrow morning.
Optional extra: think of some ways you could increase or decrease the pressure you exert on the floor.
You did the test on sound. We'll go throughy this next lesson.
We went over what forces are. We discussed why objects like tables push upward when you put objects on them, and also what can happen when the forces on an object are balanced.
You made notes on pressure, and we did some calculations about the pressure a dancer exerted on the floor.
Short HW as you did a test today. Watch this video which compares the pressure exerted on the floor by a ballerina and a tank.
We went over echolocation and did a sonar calculation.
I demonstrated an electric bell in a jar which I pumped most of the air out of.
We looked at an oscilloscope and the traces produced by different sounds, and sketched some answers to questions.
We looked briefly at loudness and hearing damage.
Revise for test in sound after half term.
Hopefully you can do some revision this week - you don't need to revise over half term.
Due to a misunderstanding about the homework, we did some more questions from the textbook and went through the answers.
We discussed ideas about how to show that sound can't travel through a vacuum.
We made notes on frequency and pitch.
I gave out the list of stuff you need to know for this topic.
Use the textbook and this video to make notes on echolocation.
Bring your notes to next lesson.
Remember that for sound reflecting off an object, distance = speed x time / 2 because the sound goes there and back.
This video is also interesting as it shows echolocation in humans.
Describing, Making & Hearing Sound
We looked at a few of your questions from the HW. Physics can help us answer some questions about sound. For other questions you might also need to explore biology, psychology, philosophy and more...
We went over the words you used to describe sound, and started to look at what affects the pitch of a sound.
We tested our hearing ranges - most people could hear from about 20Hz to 20,000Hz.
Answer Q1-3 on P52 and hand in tomorrow morning.
You may need to read some of the textbook to help you answer.
We went through the test on light.
We had a big discussion about flatness and smoothness.
You experimented with a primitive musical instrument, and we noticed a very interesting effect produced by the lights in the room. We will investigate this more next lesson.
You wrote down at least ten words that can be used to describe sound. We will go through these at the start of next lesson.
Find three questions about sound where the answer does not come up on the first page of Google.
e.g. "What is the loudest sound?" is no good - there are lots of answers on the first page of Google.
Bring your questions to next lesson.
Don't spend too long on this HW - just the usual amount of time.
Revision + Test
We went over a few questions that you had about light.
You did the test.
You did a very hard starter question on refraction through a hexagonal prism.
You did some tricky exam style questions on light and we went through most of them.
Revise for a test on light in the first lesson back after the holidays.
Refraction and dispersion
I gave out the list of stuff you need to know in this topic.
You predicted what would happen when a ray of light was directed through a triangular prism.
You then did the experiment to find out, and saw that white light was split into the colours of the spectrum.
You made notes on dispersion, and we discussed the perception of colour.
Do some revision of the material we have covered so far in this topic.
Refraction & Total Internal Reflection
We watched some people's videos of their demonstrations - well done to those of you who volunteered.
We finished off our notes on refraction from last week.
You did an experiment like this to investigate the path of light through a semicircular block.
Watch this video and add to your notes from the lesson.
Make sure you sketch the three diagrams he has on the screen.
Reflection and Refraction
We went over the stuff you learned about reflection, and looked at a tricky question involving two mirrors ar right angles to each other.
We started to make notes on refraction, and you did an experiment passing light through a rectangular perspex block.
Watch this video which shows three demonstrations involving refraction.
Recreate ONE OF THESE EXPRERIMENTS and record it on your phone. Then either post the video to Yammer or bring your phone to next lesson so we can see the videos. You can work in pairs or threes for this.
ONLY DO ONE OF THESE EXPERIMENTS - DO NOT DO ANY OTHER EXPERIMENT YOU FIND ON YOUTUBE AS IT MAY BE NOT BE SAFE!
You went through the test from last half term.
You started to learn about light, and learned some basic stuff about how light travels.
You did an experiment about reflection.
We played a game of magnetism bingo.
I gave a quick explanation about how steel is magnetized by the alignment of domains.
We did the test.
Relays, fields, making a permanent magnet.
I demonstrated a relay and we worked out how it works. If you missed the lesson, watch this video
We drew diagrams of the field around and inside the coil of an electromanget, and made notes on how to reverse the direction of the field.
You permanently magnetized a steel nail by stroking it with a bar magnet (watch this if you missed the lesson).
Next lesson I'll explain how it works.
Revise for a test on this stuff next lesson. Don't worry about the domain theory bit - I'll explain that at the start of next lesson.
The test is quite short, so there will be plenty of time at the start to go over anything you're not sure about.
We went through the HW and discussed the features of a good graph.
We finished the practical from last lesson, and plotted a graph.
I demonstrated that a core made of iron lost almost all of its magnetism when the electromanget was switched off, whereas your steel nails retained most of their magnetism when the current was switched off.
I demonstrated the operation of an electric bell, but did not explain how it worked - you will find out for HW.