See if you can also follow these two examples:

1. A ball thrown vertically down toward the ground from a 50 meter tall building with an initial speed of 20 m/s. Assuming that it falls without air friction, what is the velocity when it hits the ground?



It should make sense that we now have a faster velocity since we threw the ball downward to begin with.

2. A ball is thrown directly upward from a 50 meter tall building with an initial speed of 20 m/s. Assuming that it falls without air friction, what is the velocity when it hits the ground?



We took the initial velocity here as a negative number because the ball was thrown upward and we are calling downward positive. If a ball is thrown up at 20 m/s by the time it gets back down to the top of the roof, it is going downward at 20 m/s. So the answer comes out to the same number!

In Lower Secondary class we are covering the basic formula Speed = distance /time.

Lower Secondary Question: Given that the earth is 150 million km from the sun, find the orbital speed of the earth around the sun in km/hr. Assume that the earth’s orbit is circular and take the year to be 365 days.

Solution: The circumference of a circle is given by 2(pi)r = 2×3.14×150×10^6km = 9.42 ×10^8 km. This is the distance that the earth travels in one year. Taking speed = distance/time



As a comparison the escape velocity of a rocket traveling to Mars only has to reach a speed of 45,000 km/hr to get away from the earth’s gravity. So the earth is moving very fast around the sun !

A few students have asked me recently about the news concerning neutrinos. Here’s some info and some speculation…….

Here is what has happened: Physicists at CERN in Geneva, Switzerland produced neutrinos that were shot through the earth and detected 732 km away in the Gran Sasso Laboratory in Italy. The diagram below shows the path of the neutrinos. What is a neutrino? It is a very, very, very small particle with (we think) almost no mass. It passes through most material, which is why it can go through the earth and still be detected. What happened in 2011 is that the neutrino’s speed was calculated by the Europeans at CERN and found to be faster than the speed of light. According to our understanding of modern physics no particle can accelerate to a speed faster than light. So the scientists who made the observation are asking for other scientists with similar facilities in the USA and Japan to confirm the results.

Here are three possible explanations (and there are more):
1. The calculations are somehow in error and further experiments will correct the calculations so that the neutrino is not going faster than light.
2. The calculations are correct and the neutrino is travelling faster than light. If this turns out to be the case, the famous physicist Jim Al-Khalili has said he would eat his boxer shorts on live TV as posted in his blog here . So you can tell from this post that many scientists feel that the speed of light is in fact a hard speed limit as shown by calculations of Einstein’s theory of Relativity. I agree with this point about the speed limit as well.
3. But there is a third possibility. The results are correct BUT …the neutrino is still not traveling faster than light. How could this be? Answer: The neutrino has access to other dimensions. I believe there is strong evidence that very small things like electrons and neutrinos have access to more dimensions vs larger objects of the size of say, golf balls. When we look at a golf ball we see the whole thing. But when we look at an electron we don’t see the whole electron. We see part of it. The rest of it exists in another dimension or dimensions that only very small things have access to. So the neutrinos moving from Switzerland to Italy are able to take a shortcut through these extra dimensions. This interpretation would say that the data is correct, but the neutrino is not travelling faster than light, instead it is accessing an additional dimension or dimensions and only seems to us to be moving faster than light.
If this third possibility turns out to be the correct interpretation, then the next step is to devise an experiment that differentiates between accessing additional dimensions and faster than light travel. There is one caveat to the third explanation though. We detected neutrinos from a supernova in 1987. If they really do access other dimensions with the same time difference we see at CERN, then they should have arrived years earlier then they did. So perhaps the fact that these neutrinos pass through the earth is what changes things. Mass being around makes the difference perhaps.
Can you think of a good experiment to do next?
When we get to A-Level Quantum Mechanics this year I’ll touch on a few of the concepts related to very small objects. But stay tuned to the neutrino story – it may turn out to be very interesting. On the other hand it might just be a mistake, but we shall see…….

Answer: 633 nanometers = 0.633 micrometers

For information on our Holiday workshops and our 2012 Lower Secondary Science Classes, contact us at the link below…..

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