Space NEWS #9 (SpaceX landing!)

Hi,
in one post I already talked about the company SpaceX which is founded by Elon Musk who is a billionair and fan to Mars colonization. Right now SpaceX often delivers food and other goods on ISS helping NASA. Musk wants to make flying to space a lot cheaper and the first step for this is reusable rocket, right now to deliver one kilogram on Earth’s orbit costs about 20,000$.


I already mentioned how the company was able to land on one particular spot which was a great breakthrough. Since this would be in long term quite dangerous (to land over on continent where it could hit someone), it was needed to try this on the ocean. In the mission with Jason-3 there was some damage and the rocket exploded.

booster on the barge

SpaceX learned from their mistakes and yesterday they actually landed on a barge. The barge was named “Of Course I Still Love You” and trust me it was a real challenge, not only the last steps but also the whole process before, the barge is small compared to the vastness of ocean and yet, they were able to land just few meters next to the right spot.

Here is the link for the landing, this should left you wondering, how far can we get?

Dragallur

 

Why do formulas look like this?

Hi,
today I want to explain the formula cars and why they look like how they look like, because they have something very special, upside down wings!


Wow, ok, what is that? Well in the picture above you can notice two particular parts which you would not maybe expect when driving as fast as possible since they make the friction with air higher.

There is one infront of the car and one behind it. It is turned towards the motion of the car so that the air pushes the car back and down.

I could seem that it is not very efficient and that it only slows the driver, but lets see the physics behind it!


Formulas have one problem, they have to slow down in curve. Why? Well if they would not slow down it would throw them out of it because of the cars inertia (not centrifugal force). At the same time the driver wants to drive as fast as possible to finish the race first. When he is driving in the curve the only thing that holds him in place is the friction from tires, here it has the role of centripital force and the equation for friction is:

F=Nf

Where N is the downward force and f is the ratio between asphalt and tire. To get the highest possible centripetal force, or friction here, you need to have bigger N.

 

You would have big N if you would have heavy car but you do not want to have that since it would slow you a lot in straight line. So you put on your car those wings and it looks like this:

Formula1

The brown arrow is the direction in which the formula drives. Blue arrows are the flow of air this pushes the black part down (red arrow) and little bit back. The simple blue arrow shows where the air goes afterward.

This red arrow helps the car stay on the road because it does not fly away thanks to this even in high speeds, otherwise you would have to slow down because of the inertia.

 

Dragallur

Explaining equations easy way

Hi,
today I want to talk about simple physical equations and how you can check if they are right or not.


Lets start with the equation of distance in the most simple way.  How do you find this formula anyway? Well we want to know how distance traveled is calculated.

s=…

Now on the right side there should be something that corresponds to distance. There has to be time because we are talking about traveling in some time.

s=t…

Distance also depends on how fast you are traveling, which means velocity has to be there. Now if both time and velocity are bigger you will get also bigger distance so there will be multiplication between them.

s=v*t

From this we can conclude that:

v=s/t     this makes sense because velocity will be big when you travel for short time great distance.

t=s/v     this too makes sense because time will be great when you will go slowly great distance.

This is all intuitive, you do not remember any equations because those you can always get just from pure logic.


I can follow with the equation of inertia:

p=…

Inertia describes basicly how hard it is to stop something. Just from personal experience, when is it hard to stop something? When it is heavy and when it is fast.

p=m*v

What units will inertia have? Well you can always compare only same units so the units that come up from “m*v” must be the units of inertia.

p=m*s/t (now here we have the basic units)

p=kilograms*meters/seconds

The unit of inertia is kilogram on meter per second!


Those equations that have only two parts can be made really fast this way if you do not remember it exactly.

There is this important part with the same units. When you do some problem in physics you usually first just take all the letters and try to combine them until you get the final “sentence” and then you enter all your values. This is very effective and it is good to check you final equation, look at this for example:

P=m*g*s/t

Here it would be hard to imagine if it makes sense like we did with the formula for distance but we can get insert all the units and check if the right side is the unit for P – performance. (here m is mass, g is gravitational acceleration, s is distance, t is time). We know that the unit of performance is watt and watt is: kg*meter^2/second^3

So now for the equation we insert the values:

P=(mass*(meter/second^2)*meter)/second

P=kg*meter^2/second^3

Now we know that we are right even though we maybe started with P=W/t (W is work) and we were not sure if the conversion was right. The units correspond to what we know about performance.

Dragallur

 

 

 

 

 

Peak-end effect

Hi,
I was struggling what to write about today but finally I looked into my notes where all previous ideas for posts hide and I decided to write about peak-end effect which is something I have read about months ago though even today I think about it as something really cool. (Uhh, one sentence)

Important cognitive bias!


I found peak end when I was reading the book Organized Mind (or was it in Thinking fast and slow?). There was experiment described:

There are people in experiment. For one minute they will put their hand into bucket of water with 10°C (which is pretty cold and it hurts).

After one minute they will warm they hand back and then it continues. Another minute in bucket of 10°C water and then 30 seconds in the same bucket but with temperature secretly rised to about 12°C (you can feel the difference).

Now they asked them if they would rather repeat the first part which means one minute in 10° or the second (1 minute 10° and 30 seconds 12°) (in the original experiment the temperature may be different)

Well what would you do? Both hurt but the second clearly hurts more because it is exactly same but with another 30 seconds in which your hand will get even colder. It is clear that anyone outside the experiment would choose the first option but most if not all subjects chose the second because of peak end.


As Kahneman says, the people chose the second one because they liked the memory of it better.

The mind tends to remember ends of events and also the peaks which means both up and downs. In the experiment people remembered that the water was a bit warmer in the END so they wanted to repeat it.

Of course you can transform this situation into your life. For example I often rate my life from 0-10 points, how much I am satisfied with what I am doing here. Now every time I do it I remember how much I am influenced by the last events, the END and how much by the PEAKS (bad and good school reports, girl relationships and so on).

So yes, I think that people often make statements by the peak-end rule saying things like “my life sucks” and so on though it can influence your life in the other way, so that you think everything is fine while it may not be.

Also remember that effects like this are used by companies. It is very easy for hotel or for some holiday organization to make your feelings better when they satisfy you in the end of your visit.

Dragallur

 

 

 

 

 

Book review 5) The Blind Watchmaker

Hi,
just few minutes back I finished the book Blind Watchmaker, here is the review. (Also do not forget to check out my second blog!)

Book: The Blind Watchmaker

Author: Richard Dawkins

Genre: Science

Pages: 332

Rating: 8.1/10


Ok so compared to the first book I read from Dawkins, the Selfish Gene, this one was a bit weaker. Maybe I rated it lower because I expected something different from the book but anyway there were parts which were for me kind of boring.

This book is about the Blind Watchmaker which is natural selection. Blind because evolution does not plan ahead, it just selects the fittest.

In first chapters which were very very good Dawkins talks about probability and ireducible complexity which are favorite arguments by creationists and other anti-evolutionists. The point is that organs like eye are extremely complex, too complex to appear by chance. This should be the argument against evolution and for intelligent design. It is shown that as long as you can imagine something just a little less complex and then something just a little bit less complex than that, you will after lot of steps get to no eye at all and at all times bad sight is better than none at all, by this you can explain how complicated organs evolved over long period of time.

There is lot of text only for the echolocation of bats which is very interesting topic I recommend you to read.

Pictures from Dawkins’s simulation

Dawking puts an images of what his old computer produced when he let him run a program that changed a simple ornament into various complicated structures via simple “mutations”. He illustrates on this how species may be created.

At one point there comes a huge “disappointment”. Author is saying that the event of statue waving on you is improbable though it can happen. If all the atoms in the hand moved at the same time back and forth. He even says that his friend calculated for him the probability, and then he does not mention it!!!
What was he thinking about? That the reader would not want to know what is the probability of statue waving?! I mean, my life wont make any sense until I will found the probability somewhere… -_-

At around the page 200 it gets somewhat boring because he talks about all the schools of evolution and what all of them think, and what is right, and what arguments are good and which are not. This continues almost to the end until in last chapter he puts down creationism, lamarckism and other so called “doomed rivals” of evolution.

The start of the book was very good but the end was boring as I said. At the same time I would not want to be influenced by the effect of “peak-end” so I give 8.1/10.

Dragallur