Happy New Year!
2R 24/03/06
We tested your pinhole cameras. Making the pinhole bigger made the image brighter but more blurry.
We then did a little experiment using flat (plane) mirrors.
You found that the angle of incidence always equalled the angle of reflection. Remember that all angles are measured from the normal line.
We did some experiments using mirrors. The first showed that a flat mirror creates an image which appears to be behind the mirror (the same distance that the object is in front.
We then looked at the effects of curved mirrors.
Mirror images are virtual, and always left to right inverted.
People who failed to make the resit on Thursday lunchtime will do a resit next term now. Your grades will look much poorer however!
2L 23/03/06
We did some experiments using mirrors. The first showed that a flat mirror creates an image which appears to be behind the mirror (the same distance that the object is in front.
We then looked at the effects of curved mirrors.
Mirror images are virtual, and always left to right inverted.
HW Text book read P169-171 and answer Qs 12-15.
2R 17/03/06
We went throught the test - occasionally good. There will be a resit next Thursday lunchtime in 509.
We looked at a laser to illustrate the point that light is invisible, unless it actually enters your eye.
You can only see the path of the beam when talcum powder or dust reflects some of the light into your eye.
Light always travels in straight lines unless it hits something.
We can use this principal to make a pinhole camera.
Light travels into a box only through a pinhole and shines on an opposite screen. An upside down image of the object you are looking at therefore forms on the screen.
Any light proof box can be used to make a pinhole camera.
HW Make a pinhole camera for testing next week.
2L 16/03/06
We tested your pinhole cameras. Making the pinhole bigger made the image brighter but more blurry.
We then did a little experiment using flat (plane) mirrors.
You found that the angle of incidence always equalled the angle of reflection. Remember that all angles are measured from the normal line.
2L 09/03/06
RM absent (ill). You did some text book work on light.
HW Bring your pinhole cameras again next week - sorry! Also, have your cover work ready to hand in for next time too.
2R 03/03/06
We covered springs in series and parallel.
2 springs in parallel extend half as much as one on it's own. 2 in series extend twice as much.
Another experiment measuring the extension of springs was carried out but with homemade springs this time.
You were reminded of the existence of the elstic limit with these much weaker springs. As soon as the graph stops being a straight line, Hooke's law does not apply and the spring is permanently changing shape.
HW Revise revise revise. Density, upthrust, pressure and springs are all on the test. (and do springs worksheet if not done yet.)
2L 02/03/06
We sat the big test. We'll go through that next week.
We started light as a topic very briefly.
We looked at a laser to illustrate the point that light is invisible, unless it actually enters your eye.
You can only see the path of the beam when talcum powder or dust reflects some of the light into your eye.
Light always travels in straight lines unless it hits something.
We can use this principal to make a pinhole camera.
Light travels into a box only through a pinhole and shines on an opposite screen. An upside down image of the object you are looking at therefore forms on the screen.
Any light proof box can be used to make a pinhole camera.
HW Make a pinhole camera for testing next week.
2R 24/02/06
We performed an experiment to see how the extension of a spring varied as applied larger and larger forces onto it.
It was found that force was proportional to extension for the most part. The force divided by the extension gives us the spring constant, k of the spring which tells you how stiff it is.
Spring constant(N/m) = Force(N)/Extension(m)
A very large force can permanently deform the spring meaning it has passed beyond its elastic limit. Hookes law no longer applies after the graph has started to curve.
HW Spring worksheet which involves plotting a graph of the data given to you on the sheet. Anyone who hasn't handed their books in yet needs to by Monday for parents evening.
2L 23/02/06
We covered springs in series and parallel.
2 springs in parallel extend half as much as one on it's own. 2 in series extend twice as much.
We then recapped everything from density, upthrust, pressure and springs for a test next week.
HW Revise revise revise. (and do springs worksheet if not done yet.)
2L 9/02/06
Another experiment measuring the extension of springs was carried out but with homemade springs this time.
You were reminded of the existence of the elstic limit with these much weaker springs. As soon as the graph stops being a straight line, Hooke's law does not apply and the spring is permanently changing shape.
HW Springs sheet (including plotting a graph)
2R 03/02/06
Several demonstrations were seen. Liquids and gases can also exert forces on objects, and hence pressures (Pressure = Force/Area)
The pressure in a connected pipe of fluid is the same throughout. This fact allows us to create force multiplying hydraulic machines.
Pressure = Force / Area
The pressure is the same in both pistons as they are connected.
Force = Pressure * Area
The piston with the bigger area can exert a larger force than is used to push the smaller piston down. The smaller piston has to be pushed down further than the larger piston will move up, however.
Examples of hydraulic machines.
The particles in a liquid or gas exert a force on solid objects when they collide with them and bounce off.
The pressure in a gas or liquid rises as you go deeper into it.
We are many km below the top of the Earth's atmosphere and the pressure exerted is quite large (100000N/m2)
You saw a vacuum pump suck all the air out from inside a metal can. The pressure on the outside was then enough to crush the can. Usually, the inner and outer pressure is equal and opposite.
Similarly, a partially inflated balloon placed inside a HW Finish all the instructions on the handout sheet, (1,2 and 3 at the end of the sheet) including the appropriate questions from the book.Get your book in to me on Monday morning if it hasn't already been handed in or recieve a poor grade!
2L 02/02/06
We performed an experiment to see how the extension of a spring varied as applied larger and larger forces onto it.
It was found that force was proportional to extension for the most part. The force divided by the extension gives us the spring constant, k of the spring which tells you how stiff it is.
Spring constant(N/m) = Force(N)/Extension(m)
A very large force can permanently deform the spring meaning it has passed beyond its elastic limit. Hookes law no longer applies after the graph has started to curve.
HW Finish off experimental write up.
2R 27/01/06
We carried out an experiment to show how pressure varied with depth.
A manometer was used along with a glass bulb and stretchy rubber material to measure the pressure under water. The larger the pressure, the bigger the difference in the levels on either side of the U-tube.
The results showed that the pressure in the water was proportional to the depth under the surface.
This makes sense, as there is a greater weight of water pushing down from above the deeper underwater you go.
Pressure = Depth times Density times gravitational field strength
The above formula allows you to work out the pressure due to any fluid.
HW Get all HWs caught up, (P38, P105-106, P44-45 etc.) and finish the write up of the experiment including all of the questions from the sheet answered in full sentences in your book.
Message for Jossi: I have loads of copies of the pressure handout in my room, just couldn't find them at the time. You can come and pick one up on Monday; if not, Click this link.
2L 26/01/06
Spot test on pressure.
We tried and failed to see the effect of putting a partially inflated balloon into a vacuum. Perhaps next time.
We looked at how the upthrust force occurs due to the difference in pressure as you go deeper under the surface of a fluid in a gravitational field.
The pressure in a connected pipe of fluid is the same throughout. This fact allows us to create force multiplying hydraulic machines.
Pressure = Force / Area
The pressure is the same in both pistons as they are connected.
Force = Pressure * Area
The piston with the bigger area can exert a larger force than is used to push the smaller piston down. The smaller piston has to be pushed down further than the larger piston will move up, however.
Examples of hydraulic machines.
HW Using pressure in machines sheet.
2R 20/01/06
We covered the introduction to pressure. An experiment was performed where the same sized force was put onto various objects pushing into plasticine.
It was found that the objects with the smallest surface area made a much larger indentation into the plasticine. This is because they were exerting a larger pressure.
Pressure (N/m2)= Force (N) / Area (m2)
All sharp cutting devices use a low surface area to be able to cut into materials with very little force.
HW P44-45 Qs 1-5 (on paper) All books in now or on Monday for those who forgot theirs.
2L 19/01/06
The topic of pressure was continued. Liquids and gases can also exert forces on objects, and hence pressures (Pressure = Force/Area)
The particles in a liquid or gas exert a force on solid objects when they collide with them and bounce off.
The pressure in a gas or liquid rises as you go deeper into it.
We are many km below the top of the Earth's atmosphere and the pressure exerted is quite large (100000N/m2)
You saw a vacuum pump suck all the air out from inside a metal can. The pressure on the outside was then enough to crush the can. Usually, the inner and outer pressure is equal and opposite.
HW Finish all the instructions on the handout sheet, (1,2 and 3 at the end of the sheet) including the appropriate questions from the book.
2L 12/01/06
Half books were present, half weren't due to German shenanigans.
We covered the introduction to pressure. An experiment was performed where the same sized force was put onto various objects pushing into plasticine.
It was found that the objects with the smallest surface area made a much larger indentation into the plasticine. This is because they were exerting a larger pressure.
Pressure (N/m2)= Force (N) / Area (m2)
All sharp cutting devices use a low surface area to be able to cut into materials with very little force.
HW P44-45 Qs 1-5 (on paper all books in now)
