RM 08/09/04 3C
Exercise books were issued. Safety notices were stuck in.
Text books "Spectrum Physics" were issued. Numbers of text books were recorded.
Forces were looked into as the first topic. A force is a push or a pull which changes the motion of objects. If an object is at rest or at a constant speed, it must have no overall force on it. This usually means that it has equal and opposite forces on it. An object sitting on a desk has a reaction force acting against its weight to keep it still.
We did an experiment investigating friction. The larger the weight of an object, the larger the frictional force it can produce. We discovered this because it took a larger force to start moving a block when it had masses piled on top.
Once an object has started sliding, the frictional force on it decreases. It took less force to keep the block sliding at a constant speed than it did to start it moving in the first place.
HW Finish Qs 7,8,9,10 from the sheet and then do diagrams for points 4 and 5 in your book.
RM 08/09/04 3A
Exercise books were issued. Safety notices were stuck in.
Text books "Spectrum Physics" were issued. Numbers of text books were recorded.
Forces were introduced as a topic. They can be mechanical (when touching objects exert a force on each other), or act at a distance like gravity and magnetism. If an object has an unbalanced force on it, it will change speed or direction. If an object is moving at a constant speed or is at rest, the forces on it must be balanced.
RM 13/09/04 3A
We did an experiment investigating friction. The larger the weight of an object, the larger the frictional force it can produce in contact with a surface. We discovered this because it took a larger force to start moving a block when it had masses piled on top.
Once an object has started sliding, the frictional force on it decreases. It took less force to keep the block sliding at a constant speed than it did to start it moving in the first place. Static friction is larger than dynamic friction.
HW P39-41 Spectrum Physics all questions (finish off classwork if not done in lesson) Books handed in next lesson.
RM 14/09/04 3C
We looked at a ball bearing falling through oil (glycerol). The thick, viscous fluid was able to demonstrate to us how drag forces in fluids (liquids and gases) work. The ball bearings accelerate downwards due to their weight when dropped. The faster the ball bearings go, the larger the drag on them due to the liquid. When the drag reaches the same size as the weight of the ball bearing, the ball bearing stops accelerating and moves through the liquid at a constant speed. (NB: Objects moving at a constant speed or at rest have balanced forces acting on them.) Qs on friction were attempted. Books were taken in.
RM 15/09/04 3C
We looked at different methods of measuring an object's average speed. You need to know the distance it travels in a certain time
Average speed = Distance/Time
A light gates measures the time taken for a certain length object to pass through a beam. A ticker tape timer puts a dot down every 1/50th of a second. You can measure the distance that the ticker tape has moved in this time using a ruler.
HW Finish ticker tape timer write up in your book and do sheet of ticker tape calculations.
RM 15/09/04 3A
We looked at a ball bearing falling through oil (glycerol). The thick, viscous fluid was able to demonstrate to us how drag forces in fluids (liquids and gases) work. The ball bearings accelerate downwards due to their weight when dropped. The faster the ball bearings go, the larger the drag on them due to the liquid. When the drag reaches the same size as the weight of the ball bearing, the ball bearing stops accelerating and moves through the liquid at a constant speed. (NB: Objects moving at a constant speed or at rest have balanced forces acting on them.)Books were taken in.
RM 20/09/04 3A
We looked at different methods of measuring an object's average speed. You need to know the distance it travels in a certain time
Average speed = Distance/Time
A light gates measures the time taken for a certain length object to pass through a beam. A ticker tape timer puts a dot down every 1/50th of a second. You can measure the distance that the ticker tape has moved in this time using a ruler.
HW Do sheet of ticker tape calculations.
RM 21/09/04 3C
We looked at the idea of acceleration, the rate of change of speed.
Acceleration = Change in speed/Time
We specifically looked at measuring acceleration using an air track. 2 light gates were required to measure the 2 speeds, and a stopwatch to measure the time taken between obtaining the 2 speeds. HW sheets were taken in.
RM 22/09/04 3C
We once again did some acceleration calculations. This time we used a ticker tape timer. First of all we used the ticker tape to create a graph representing how the speed of an object changed over time. Then we attached the ticker tape to a trolley which rolled down a slope. The acceleration could be calculated once again by:
Acceleration = (final speed - initial speed)/time to change speeds
or a = (v-u)/t
The ticker tape tells you all of this information, as you can just calculate 2 speeds, and then count the gaps between dots which occur between each of the speeds. Each gap between dots represents 0.02 seconds. (1/50th of a second)
HW Sheet of fill in blank questions on ticker tape timers and acceleration.
RM 27/09/04 3A
Having missed Wednesday's lesson, we had to motor on. Firstly, we used 2 light gates along the air track to measure the speed of a trolley as it gently got faster down a slope at 2 points. (Speed = Distance/Time)
A stopwatch recorded the time taken for the trolley to get between the 2 light gates.
Acceleration = (Final speed - initial speed)/time
It is the rate of change of speed.
We then used a ttt, to calculate accelerations. The acceleration could be calculated once again by:
Acceleration = (final speed - initial speed)/time to change speeds
or a = (v-u)/t
The ticker tape tells you all of this information, as you can just calculate 2 speeds, and then count the gaps between dots which occur between each of the speeds. Each gap between dots represents 0.02 seconds. (1/50th of a second)
HW Sheet of fill in blank questions on ticker tape timers and acceleration.
RM 28/09/04 3C
We used a ticker tape to measure the acceleration of 2 bodies as they fell, the acceleration due to gravity. The 2 bodies had different masses, but both accelerated at roughly the same rate - we will discuss why next time. However, our results were under the actual acceleration due to gravity, which is more like 10 m/s/s.
RM 29/09/04 3C
We looked at representing motion in the form of graphs. You can tell a great deal about the motion of an object with its speed against time graph. A constant acceleration appears as a straight sloped line. In free fall, objects experience an accelerating force which is their own weight. Heavier objects therefore experience a greater accelerating force. It takes a bigger force to accelerate heavier objects, and the 2 factors exactly cancel each other out, meaning that all objects accelerate at 10m/s/s under Earth's gravity. Guinea and feather experiment showed (unconvincingly) that a coin and some polystyrene fall at the same rate in the absence of air.
HW: All Qs P 136-139 from Spectrum Phys
RM 29/09/04 3A
We looked at representing motion in the form of graphs. You can tell a great deal about the motion of an object with its speed against time graph. A constant acceleration appears as a straight sloped line. For a constant acceleration, the average speed of an object is exactly half of its maximum speed. This allows you to do a calculation of the acceleration due to gravity knowning only how far an object has fallen, and how long it has taken.
The above is true because all objects accelerate at the same rate under gravity. In free fall, objects experience an accelerating force which is their own weight. Heavier objects therefore experience a greater accelerating force. It takes a bigger force to accelerate heavier objects, and the 2 factors exactly cancel each other out, meaning that all objects accelerate at 10m/s/s under Earth's gravity.
RM 04/10/04 3A
We continued to look at falling under gravity. Firstly, the guinea and feather experiment showed that objects of all masses fall at the same rate provided that air resistance is not an important factor. (also we saw video footage of a hammer and a feather being dropped on the moon.) We then looked at horizontal projection. An object projected horizontally sideways still falls vertically downwards at the same rate as an object which is just dropped. The horizontal speed is irrelevant to the rate that an object accelerates downwards under gravity.
HW Revise for a test on motion and forces which will be next Monday. We'll do some practise questions on Wednesday.
RM 05/10/04 3C
An object projected horizontally sideways still falls vertically downwards at the same rate as an object which is just dropped. The horizontal speed is irrelevant to the rate that an object accelerates downwards under gravity. You can always completely seperate the horizontal and vertical motion of an object.
Books taken in.
RM 06/10/04 3C
Books were not marked! Practise questions were done for a test next Tuesday on forces and motion.
Acceleration = Change in speed / time = (v-u)/t
In ticker tape timer questions, the time can be calculated by counting the number of gaps between dots which occur between the 2 speeds. The speeds are actually calulated in the middle of the gap between dots, so this should be taken into account.
HW Revise for test.
RM 11/10/04 3A
We sat the test on forces and motion and watched vid.
RM 12/10/04 3C
We couldn't sit the test, it is too long. Never mind, we'll do it tomorrow, another day to revise for you lucky lot. Instead we watched a video on freefall.
HW Revise for the test again. Also make sure you have last week's homework ready to be marked in your books as they will be taken in tomorrow.
RM 13/10/04 3C
We sat the test on forces and motion.
We began the topic of energy and energy transfers. Energy is a measure of the ability to do work. It is measured in Joules and comes in many different forms.
We looked at an electric motor lifting up a mass. It used 1.36 Joules of electrical energy to lift up a 0.1kg mass by 0.5 metres. The gravitational potential energy (GPE) given to the mass (energy it has gained by being lifted up higher) can be calulated.
GPE = Mass times gravitational field strength times height lifted.
GPE = 0.1 times 10 times 0.5 = 0.5 Joules
Where did the extra energy go?
HW Draw diagram of the apparatus and write out all the energy changes involved.
RM 13/10/04 3A
We "went through" the test. It was done fairly well in general, few require a complete overhaul however....JC, BN and RB will see me on Monday lunchtime at 1.10pm.
RM 18/10/04 3A
Aha. CCFers were tired. We talked about energy "the capacity for things to happen". When energy changes from one type into another type, then "things" happen. There are several different types of energy: kinetic energy (movement), gravitational potential energy, heat energy, sound energy, light energy, chemical potential energy, elastic potential energy, nuclear energy, electrostatic potential energy etc.
HW Answer Qs 1-7 from P5+6 of your Spectrum Phys. books.
RM 19/10/04 3C
We went through the test. Everyone did pretty well, just a few points on some of the harder questions missed in general.
We continued talking about energy, and looked at the idea of efficiency. This is the percentage of energy that is usefully extracted from something compared to the total energy you have put into it.
A device that converts energy from one form to another (does work) is called a transducer.
RM 20/10/04 3C
We watched a vid on energy conversion and energy resources. Then we did some questions from the text book. Nearly all forms of energy available to us on Earth are either directly or indirectly sourced from the Sun.
HW To complete the energy transfers involved in generating electricity from: coal, oil, wind power, and nuclear.
RM 20/10/04 3A
We looked at the efficiency of a motor lifting up a mass. The percentage of "useful energy" that is extracted from a machine compared with the total energy required to run it is known as the efficiency of the machine.
RM 01/11/04 3A
We saw a vid on renewable energy sources. They are generally derived from the Sun (as are fossil fuels) and will last as long as the Sun shines on the Earth. Geothermal energy uses the Earth's internal heat energy (which doesn't come from the Sun) and tidal energy allows the Moon's energy to be tapped. There are problems with all renewable sources, mostly that they are still more expensive than using fossil fuels.
HW Do Qs 1-7 on P12-13 Spectrum Phys. Those who missed last set (Qs 1-7 P5+6) must get them caught up by Wed.
RM 02/11/04 3C
RM absent. Questions from Spectrum Phys. P8+9 And P12+13 were attempted.
RM 03/11/04 3C
RM absent again. Questions from Spectrum Phys. P59-64 were attempted on heat and temperature.
RM 03/11/04 3A
As 3C but P59 to 62 only.
RM 08/11/04 3A
We talked about heat energy and temperature. Heat energy is the energy something has due to the internal movement of its particles. When you heat something up, you are making its particles move faster, in a solid they vibrate, in a liquid and a gas they are able to move around each other.
The temperature of a body is a measure of the average kinetic energy of its particles. It is often measured in degrees Kelvin in science. They are the same as Celsius except that O Kelvin is the temperature at which particles would completely stop moving, and so things cannot possible be any colder than that. It is at -273 degrees celsius - absolute zero.
When you give an object some heat energy, it will warm up. The amount that it warms up by depends on its heat capacity.
The heat capacity of an object is the amount of energy required to heat it up by 1 degree.
The specific heat capacity of a material is the amount of energy required to heat up 1kg of the substance by 1 degree.
HW Questions on specific heat capacity.
RM 09/11/04 3C
We went through the introductory questions that you did whist I was absent.
Heat energy is the energy that something has due to the internal movement of its particles and is measured in Joules. Temperature is a measure of the average energy of the particles of something. Degrees Centigrade are a useful way of measuring every day temperatures based on the boiling and freezing point of water at atmospheric pressure. However, it makes more sense to start the temperature scale from the point where particles would be absolutely still (have zero kinetic energy). This would happen at -273 degrees C. The scale which starts at this "absolute zero" is called the Kelvin scale. 1 Kelvin is the same size as one Celsius it's just that they have different starting points.
HW None, books taken in from those present.
RM 10/11/04 3C
We heated up 3 samples of metal with the same amount of electrical energy (monitored by a Joulemeter). 1kg of each type of metal was used, but they changed in temperature by different amounts. The smaller the change in temperature, the larger the specific heat capacity of the metal being tested. The energy required to heat 1kg of a material up by 1 degree Celsius is its Specific Heat Capacity. Water was hard to measure because so much energy was lost to the surroundings when heating it. Our answers for the metals were better, but still likely to be too high due to the energy being transferred to the surroundings aand not into the metal.
HW None, for those who are up to date. I took the rest of the books in. You must have cover work marked as well as the most recent HW by next week.
RM 10/11/04 3A
We did some more example calculations on specific heat capacity. SHC HW sheets were taken in. Those absent, get them in by the end of the week please!
RM 15/11/04 3A
We looked at 3 demonstrations of conduction of heat. Conduction is where heat energy is transferred through a material via collisions of particles. As hotter particles move faster, they tend to hit other particles and give them more energy, passing energy heat along the material.
Metals conduct heat the best as they have free electrons which can move through the material carrying heat energy as they go. Liquids and gases are poor conductors as particles collide far less often in this state.
HW P62-64 Qs 1-11 Spectrum Phys. (you will have started these as cover work last week).
RM 16/11/04 3C
We finished off specific heat capacity. You must be familiar with using the equation to calculate the amount of energy required to heat some substance by a certain amount. OS has catch up RS better find his book. Tomorrow - conduction of heat.
RM 17/11/04 3C
Soilds conduct better than liquids or gases (particles closer together). Metals conduct best (free electrons can carry heat energy through the structure).
Black objects absorb heat radiation best (as they do light) and so warm up the most when infra red is shone on them. White or silver objects reflect most heat radiation and heat up less.
Black objects emit heat radiation best too, so if a hot object is black, it will emit more radiation than a white or silver object at the same temperature.
RM 22/11/04 3A
Having missed the single lesson on Wed, we went on to look at the 2 other methods of heat transfer, radiation and convection.
Radiation of heat: Heat energy can travel through a vacuum in a straight line away from a warm object. This is know as heat radiation or infra red radiation. It is just like light, but invisible to the naked eye.
Black objects absorb heat radiation best (as they do light) and so warm up the most when infra red is shone on them. White or silver objects reflect most heat radiation and heat up less.
Black objects emit heat radiation best too, so if a hot object is black, it will emit more radiation than a white or silver object at the same temperature.
Convection: Happens in liquids and gases (fluids) that are in a gravitational field. One part of the fluid is heated and the particles begin to move faster and in doing so, get further apart. This reduces the density of the warm part of the fluid. The warm part of the fluid therefore starts to "float" up above the cooler less dense fluid surrounding it. Cooler fluid then moves in from the side to replace the warm, less dense, rising fluid. This fluid then starts to be heated, and so rises itself. Once the warm fluid has risen, it may cool and start to drop back down past the warmer fluid being heated beneath it. This causes a circular convection current to be created.
HW: Do double sided sheet of questions on conduction and radiation. Books were taken in to mark last weeks HW.
RM 23/11/04 3C
Convection: Happens in liquids and gases (fluids) that are in a gravitational field. One part of the fluid is heated and the particles begin to move faster and in doing so, get further apart. This reduces the density of the warm part of the fluid. The warm part of the fluid therefore starts to "float" up above the cooler less dense fluid surrounding it. Cooler fluid then moves in from the side to replace the warm, less dense, rising fluid. This fluid then starts to be heated, and so rises itself. Once the warm fluid has risen, it may cool and start to drop back down past the warmer fluid being heated beneath it. This causes a circular convection current to be created.
We saw 2 demonstrations of convection: 1 - tea leaves in a beaker of water heated by a Bunsen, 2 - a mock up of a mine with 2 vertical shafts and a candle lit under one of them (this allowed fresh air to be drawn into mines).
RM 24/11/04 3C
Books were taken in last time to mark conduction and radiation write ups. They were terrible for the most part. You will have to learn to take in what goes on in lessons more. therefore the practical was cancelled and we did some more notes on conduction, convection and radiation. Black emits heat radiation best (when it is warm) as well as absorbing it best (when it is illuminated with infra red).
Solids expand when heated, but convection cannot occur within them as particles are fixed.
Answer Qs 1, 3, 4, 5, 6 from expansion of solids sheet.
RM 24/11/04 3A
We described why the breeze tends to go from sea onto land on a sunny day and the other way round at night (an application of convection currents). We saw a graphic example of warm air rising by putting a hot air balloon above a Bunsen burner. The balloon catches warm air which is less dense due to the particles moving faster and therefore being on average further apart. It rises along with the air, this is how hot air balloons work, they create their own personal convection currents.
RM 29/11/04 3A
Solids expand when heated due to their indiviudual particles vibrating more and getting slightly further apart on average. We heated samples of 3 different metals and measured how much longer each sample got using dial and angle scale.
HW Complete the write up with a clear method explaining how you worked out the extension of each material, a results table and a conclusion discussing the results.
RM 30/11/04 3C
2 demonstrations - the bar breaker demo showed that heating a metal causes it to expand very powerfully and the bimetallic strip shows what happens if you stick 2 metals together which expand at different rate (the strip bends). Bimetallic strips can be used as part of heating circuits to act as a thermostat.
Tomorrow, we'll do the class thermal expansion experiment that was abandoned last week.
RM 01/12/04 3C
We did a class practical expanding samples of metals by heating them with a Bunsen. Solids expand when heated due to their indiviudual particles vibrating more and getting slightly further apart on average.
HW Finish experimental write up detailed on the handout, also finish the Millennium bridge questionsheet.
RM 01/12/04 3A
2 demonstrations - the bar breaker demo showed that heating a metal causes it to expand very powerfully and the bimetallic strip shows what happens if you stick 2 metals together which expand at different rate (the strip bends). Bimetallic strips can be used as part of heating circuits to act as a thermostat.
FK,AG,AR,TB,AC all got lines in for Thursday.
RM 06/12/04 3A
We went through the conduction and radiation HW sheet which was poorly done in parts - always talk about the effects of heating on individual particles. Remeber that black absorbs and emits heat radiation the best.
We puzzled as to whether it was better to put milk in your coffee first or to leave it until later if you are going to have to leave it for a while.
The shape of the cooling curve was discussed, also a series of questions on heat were answered.
HW - None for good people. Others need to catch up. Check the site and do any work which you haven't recieved a mark for. You know who you are.
RM 07/12/04 3C
The lab hot air balloon was observed, it rises due to the particles in hot air being further apart than those in cold air (as they are moving faster), making the air less dense. It floats up on the rising air which is part of a convection current.
Questions were answered on convection and on thermometers. Remember - radiators in your room heat the place by convection currents, not thermal radiation. That is why they can be painted white without effecting their efficiency.
RM 08/12/04 3C
The cooling a cup of coffee conundrum was experimentally modelled and solved. If you are forced to leave your coffee for a period of time, it is better to put the milk in prior to leaving it, rather than afterwards.
This is because the black coffee will have a higher temperature than the white coffee to begin with. This means that the difference in temperature between the black coffee and the surrounding atmosphere is larger. This means that more heat energy is transferred from the black coffee to the atmosphere during the time you leave it. You then have to add the milk anyway, which will cool it further.
The cooling curve of an object starts off steep and gets less steep as the object gets nearer to the temperature of the atmosphere around it.
Methods of insulating your home were discussed, loft insulation, cavity wall insulation and double glazing etc.
HW Revise for a heat test on Tuesday.
RM 08/12/04 3A
Home insulation was discussed. All are ways of preventing the loss of heat energy from your home. You voted to have the test on Monday - so it shall be.
HW Revise for a test on heat for Monday.
RM 13/12/04 3A
We sat the test and then watched a vid on Brownian motion, start of kinetic theory topic that we'll begin next term.
RM 14/12/04 3C
We sat the test. We'll go through it Wed.