I have a funny story. Many years ago me and my dad had talked about how rockets worked in space. We had the understanding that rocket pushed “on” something, like the ground, to be able to exert a force on itself. So when in space it seemed strange that a rocket should work because there’s nothing to “push on”.
After learning about newtons third law I came to understand that this was not the case, then I moved on. It seems that I’ve never spoken about the subject with my dad again because a week or so ago he came home very happy because he had figured out how rockets work! Apparently he had learned Newtons third law somewhere during the day.
This got me thinking to how many people there must be out there that don’t know these fundamental physical laws that explain how things in our every-day world work. Like why dice hanging from a mirror in a car seem to “be still” for a while when the car accelerates and such. You know, things you actually do see every day.
That’s why I want to start a blog-series on this blog that I will call Physics Friday; and this is the first post. If you like it, I will keep it going. Starting off, I want to introduce you to khanacademy.org, a very smart guy that has made around 1500 instructional videos on practically every topic in science. I will use his three videos on Newtons three laws in this post. If in the future you want me to cover a subject differently or a subject that he hasn’t covered, I will make a video myself.
Obviously I can never add something that you can’t find on his site or somewhere else on the internet, so the idea is kind of to specially adapt the material to you loyal readers of this blog. My purpose is to either sift out the good stuff out there or to create something that uniquely explains your question. So lets start off!
Newtons three laws
The first law essentially covers inertia, but the video is simpler than that. It explains why it requires force to move or stop things. It’s a bit slow in the start but bear with it, it’s worth it.
The second law covers what force, acceleration and mass is. It talks about the difference between weight and mass. (In Sweden we incorrectly say we weigh 75kg, when that’s actually our mass). It shows some nice examples of calculation as well.
Newtons third law is the “how rockets work in space”-law. It explains that every force has a force in the exact opposite direction, some people call it “Every action has a reaction”. It is by far the most interesting law.
Did you enjoy the videos? Answer the polls below to give me an idea of how (and if) I’m supposed to continue with this blog series. Please, please leave comments on these posts as well with ideas of what you want explained. I will try to answer any questions you have and try to explain it so that anyone could understand it! So, what do you think?
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