Newton’s Laws Explained With Lego

Everyone who studies any science at school will have come across Newton’s Laws of Motion. His three physical laws explain the relationships between the forces acting on a body and the motion of that body and were first published in 1687 in his magnum opus – Philosophiae Naturalis Principia Mathematica.

Newton’s laws underpin so-called classical mechanics, as opposed to quantum mechanics or relativity theory. I’ve summarised them below, but you’ll get a much clearer understanding of bodies in motion if you watch the video.

1. Objects stay still or move with constant velocity unless a force pulls on them or gives them a shove
2. Pulling or shoving an object changes its velocity (accelerates it) at a rate proportional to the force of the pull or shove
3. If you shove or pull an object it will pull or shove back with an equal and opposite force

And remember, gravity isn’t just a good idea, it’s the law!

22 thoughts on “Newton’s Laws Explained With Lego”

1. No, there just three laws ascribed to Newton:

First law: The velocity of a body remains constant unless the body is acted upon by an external force.

Second law: The acceleration a of a body is parallel and directly proportional to the net force F and inversely proportional to the mass m, i.e., F = ma.

Third law: The mutual forces of action and reaction between two bodies are equal, opposite and collinear.

2. Anonymous says:

There are many laws of Newton

3. Yuffie says:

This, was brilliant :D First of all: great video! Really great animation. Second of all: thanks for the easy explanation of Newton’s three laws. I still have some difficulties understanding the second law but I think I’m getting the hang of it.

4. Naomi, someone would be able to answer your question if it were written a little more clearly. As it stands, I cannot make head nor tail of what you’re trying to say.

5. naomi says:

what are yhu guys tlkn bout??/!!!!!! js playn i was thinkn to what will happn if we dont have gravity would they think of something else wat or where would we be now without it i think we might of created something or would we?????????????? lolx

6. @Dennis It’s odd that you say gravity is a law and that it cannot be changed…well isn’t there a certain 20th Century physicist who would beg to differ and suggested that gravity is little more than a distortion of the spacetime continuum due to the presence of mass? Maybe I misunderstood what you were alluding to, and yes, the data still looks the same at the levels we observe in our everyday lives.

7. Dennis Murray says:

The operating fields of gravity is to direct an object to a equal zero point of effect, or a notable (none) effect. Gravity is a Law, and cannot be changed, but its established fields of operation can be manipulated.
Just image gravity as the subject and under this subject are three categories. Each of these categories are a sub-operating field, and together they produce the end-result, which are expressed by Newton, and your video.

8. I’d love to find some more Lego animations explaining scientific principles, anyone care to mock up a Lego train with a flashlight and a miniature Einstein figure to do relativity?

db

9. Awesome – definitely blogroll-worthy. : )

10. Coming soon Einstein’s Theory of Relativity in Meccano! (I wish)

db

11. Oh, by the way, Newton postulated the existence of gravity not because an apple fell on his head, but because he observed a comet and realised it was somehow being swung around behind the sun.

12. Zach Macias says:

Hey everyone! This is Zach M., the creator of the video.

I’m glad you liked the movie, and I am aware of a few errors in my science. But nonetheless, I’m still glad you enjoyed it!

13. David Bradley says:

That’s an interesting perspective Andrew. perhaps important to mention that matter and energy are equivalent, so it’s not just materials that you’re talking about interacting with time, but energy too. The only other problem is that time itself doesn’t exist within the framework of relativistic theory. We have spacetime, of course, and in classical mechanics space appears to be a three-dimensional framework within which objects move and energy flows, time then seems independent of mechanical motion. But relativity tells us that time is not distinct from space, it’s just that we perceive it different, the 3D nature of flat people in flatland is a good analogy.

14. Andrew Sun says:

What do we call a statement when it is proving or trying to prove the existence of something rather than how something works? I think this issue reached the field of philosophy. In my opinion (or belief, sorry), things that are existence (matter) MUST be moving/changing. Existence is the space aspect of matter, while movement/change is the time aspect of matter. Since time and space is always related, there is nothing that moves/changes but does not exist, or exists but does not move/change. Matter is the complex of time and space. The interaction/relationship between time and space is shown by and only by matter.
So when we talk about how things are working, it is equal to say we are talking about how things are existing.

15. Cliff Bowman says:

When we say “theory,” could we be talking about how gravity works rather than whether it exists? The parallel that Mr. Bradley makes to the “theory” of light is a good one: even as people debated the “theory” of light, no one seriously doubted whether the phenomenon of light existed. What people were really talking about was how light worked, and “theory” described all the various explanations that were offered.

In terms of gravity, I know of no serious debate about whether things with mass exert an attractive force on one another. What is still being worked out is how that attractive force works. One example of this is the theory of gravity waves, which is an idea credited to Einstein. This idea is based on the proposition that nothing can travel faster than light — not even the effects of gravity. Just like the light that we see from distant stars, the effects of gravity from those stars takes a long time to reach us.

Suppose something (like the interaction of binary neutron stars) causes a big fluctuation in the gravitational field. The “theory” says that won’t know that the fluctuation occurred until it propagates across space like a wave to where we are. A “gravity wave” is an attempt to explain how gravity works, and it is very much a “theory” because no direct experimental evidence exists to prove it.

Active research has been going on in this area for a long time. If you’re curious, please see the LIGO project at

http://www.ligo-la.caltech.edu/

for an example of current work. You can also search the web for references to Joseph Weber and “Weber bars” for some previous valiant but unsuccessful efforts to detect these waves.

16. David Bradley says:

Well spotted Cliff…I wonder if we can get the guys who produced the video to re-shoot it…?

Anna, thanks for that question. Gravity is most definitely a theory. A very well tested theory but nevertheless a theory. Science can only observe, hypothesize, re-test and theorize. Just because every time until now that apple has fallen to the ground from the proverbial tree, does not strictly mean that it will happen tomorrow. It’s pretty certain it will, but as soon as an experimental result that conflicts with a theory is observed, science has to re-test and if the conflicting result appears again then the theory has to be revised, or if those new results conflict completely then the theory would have to be discarded and a new theory devised to explain the results.

Gravity is not the best example of this process in action because, like I say, it’s 99.999999999% certain that it happens. But, take the classical view, the theory, of light as a wave…in the late nineteenth and early twentieth century scientists began to record experimental results that conflicted with this theory, they demonstrated that light was not a wave, but sometimes appeared to exist as a stream of particles, which we now call photons. Light is a “wavicle” a dual entity, a wave-particle. The old theory was wrong, the new theory is “right”, at least until conflicting experimental results are observed.

17. Anna Jones says:

how is gravity a theory? things fall toward the ground no matter how long it takes the object to get there. something has to cause objects to go toward the earth and other celestial bodies. example- a friend throws a ball at you it hits you and it falls to the ground. no matter how long something stays in the air it will fall. at least with objects of certain mass of course. particles tend to float but they eventually form something.

18. Cliff Bowman says:

Great video, but there’s an error in the acceleration calculation.
Change the mass of the ball to 0.2 Kg before dividing. The acceleration is really 2000 m/s^2.

19. Anthony Dihn says:

that was a very precise video
very nice apple

20. David Bradley says:

The apples are great…

As to gravitational theory, it is indeed just a theory, and Newton’s version of the theory is very much old school as you well know, Robert!

21. Andrew Sun says:

Terrific! I like the ‘apple’.