In this magic trick, the oil and the quartz glass rod have the same index of refraction. So the light doesn’t change speed or direction when it passes from the oil to and quartz glass rod.
Light is Magic
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Category Archives: Physics 11
Nuclear Debate
Though the debate we did on Friday. I think that it is fine to use nuclear but we can’t rely on it, it is dangerous and people might get hurt from it badly.
These are the benefits that we think during the debates.
1. Nuclear Power Generation Unlike fossil fuel power generation, which emits huge amounts of pollutants into the atmosphere, nuclear power generation will not create air
Pollution.
2. Nuclear power generation won’t produce carbon dioxide that aggravates the global warming effect.
3. Uranium fuel used in nuclear power generation has no other uses than power generation.
4. The energy density of nuclear fuel is millions of times higher than that of fossil fuels, so the fuel used by nuclear power plants is small in size, transport and storage
Are very convenient, a 1000 megawatt nuclear power plant only 30 tonnes of uranium fuel a year, a voyage of the aircraft can be completed
give away.
5. Among the costs of nuclear power generation, the proportion of fuel costs is relatively low, and the cost of nuclear power generation is less likely to be affected by the international economic situation
Therefore, the power generation cost is more stable than other power generation methods.
And these are the bad things that we talked about:
1. Nuclear power plants will produce high-level radioactive waste, or nuclear fuel used, although the share of small size, but because of having
Radiation, it must be handled carefully and subject to considerable political distress.
2. Nuclear power plant thermal efficiency is lower, so than the average fossil fuel power plant to emit more waste heat to the environment, so the heat of nuclear power plant
Pollution is more serious.
3. The investment cost of nuclear power plants is too large, and the financial risks of power companies are high.
4. Nuclear power plants are less suitable for spikes, peak-load operation.
5. Construction of nuclear power plants are more likely to trigger political disagreements.
6. There are a large number of radioactive substances in the reactors of nuclear power plants. If they are released to the external environment in an accident, they will be made to the ecology and people into injury.
Wooden Arch Bridge
History
Wooden Arch Bridge, also called Mathematical Bridge. It was designed by William Ethelich II and was built by James Essex in 1749. The Mathematical Bridge is located in Cambridge, England, spanning Cambridge on the campus of the University of Cambridge, connecting the Queen’s College to the campus on both sides of the River. The Mathematical bridge reconstruction in1866 and 1905, but the original design has not changed.
In the short term, the wooden arch bridge can use to let people across the river. In long term, it can be used to build a stone arch bridge.
The Wooden Arch Bridge in China The Mathematical Bridge in England
Physics Involved
Kinetic energy and Potential energy when the car through the bridge.
Ek=1/2mv^2 Ep=mgh
The Newton’s Third Law, forces result from interactions. So the Fn from ground equal to opposite Fg of the bridge.
And forces we haven’t touched yet:
Design and Building
Day 1
We discussed and decided to make an arch bridge. Then we searched some information on our machine.
Day 2
We drew a draft of our machine and build a model only with some chopsticks, but we failed.
Day 3
We build a little arch bridge first: using chopsticks, glue and glue gun.
Day 4
Based on the little arch bridge, we add some chopsticks on both sides to make it longer.
Day 5
To make the bridge looks better and real, we paint color on the bridge.
The hardest part of this chopstick arch bridge is if we don’t glue it, it is hard to make because we need to make the chopstick hold each other and do not fall. And also it is hard to fix out how to let the chopstick hold each other, where to put each one.
5 web that I look up
https://en.wikipedia.org/wiki/Arch_bridge
https://en.wikipedia.org/wiki/Mathematical_Bridge
https://www.queens.cam.ac.uk/life-at-queens/about…/mathematical-bridge
https://dailysliceofpi.wordpress.com/2013/07/…/newtons-mathematical-bridge
https://zh.wikipedia.org/zh-hans/數學橋
Wave Interference
Constructive Interference
The interference of two or more waves of equal frequency and phase, resulting in their mutual reinforcement and producing a single amplitude equal to the sum of the amplitudes of the individual waves.
Destructive Interference
The two pulses completely destroy each other when they are completely overlapped.
Standing Wave
The wave doesn’t propagate. It just sits there vibrating up and down in place.
Exploring Waves LAB
Pulse Wave
A kind of non-sinusoidal waveform that is similar to a square wave, but does not have the symmetrical shape associated with a perfect square wave.
Periodic Wave
A series of regularly timed disturbances in a medium.
Transverse Wave
A wave vibrating at right angles to the direction of its propagation.
Longitudinal Wave
A wave vibrating in the direction of propagation.
Newton’s Law
Newton’s First Law
Any object must maintain a uniform linear motion or static state, until the external force to force it to change the state of motion so far.
The skateboard starts from the rest with same speed and direction until the skateboard crushes the book, it stopped. The book changes the motion of the skateboard.
Newton’s Second Law
The magnitude of the object acceleration is proportional to the force of the object, inversely proportional to the mass of the object, and is proportional to the reciprocal of the mass of the object; the direction of the acceleration is the same as the direction of the force.
The same skateboard, when we add two books on it, it changes the mass. So the speed gets lower. We need to put more force on push the skateboard to make the skateboard going the same speed as the first test.
Newton’s Third Law
The interaction between the two objects and the reaction force is always equal in size, the opposite direction, the role of the same line.
When the hand first hit the table, is not hurt because the force effect is small, so the reaction force is small. The second hit is hurt because the force effect is hard, so the reaction force is hard too.