Newton’s Laws

By Ben Morgan

James Newton

• Lived from January 4th, 1963 to March 31st, 1727

• Became interested in physics, specifically Galilean physics from a relatively young age

• If Galileo is the father of modern science, then Newton is considered the father of modern physics.

His Contributions

• Helped the modern color spectrum be developed.

• He did this through his study of optics.• In addition to Leibniz, he developed Calculus• Using Calculus, he did perhaps his most

famous work and developed his Three Laws of Motion

The Three Laws

• The Three laws of motion are universal laws that account for every object in motion.

• This includes everything from rolling a ball down a hill, to the motion of the planets.

• The laws were so precise that we used the same laws to land the Eagle Lander upon the moon!

Newton’s First Law

All bodies remain at rest or remain at a constant speed unless acted upon by an outside force.

-So if you roll a ball down an incline that eventually levels out and is frictionless, the ball will continue rolling that direction forever.

Newton’s Second Law

• The force acting on a body is equal to the time change of linear momentum on that body.

• It’s as bit complicated, but what it essentially means that the total force acting on a body is equal to the mass of that body multiplied by its velocity over time.

• So F=ma

The Third Law

Third Law

• All actions have an equal and opposite reaction.

• So when someone fires a gun, the force exerted from the gun is the exact same force moving in the opposite direction, hence recoil.

How?

• Now that we know how the laws work, the question comes to mind as to how Newton was able to discover these laws.

• In popular culture, he was sitting under an apple tree when an apple fell nearby.

• In a sudden rush of logic, he realized that the same force pulling the apple to the ground was the same force keeping the moon in orbit: Gravity!

Alright…

• So what’s keeping the moon in orbit? Well, gravity of course. But how does gravity work?

• All objects that contain molecules have mass. Mass is the quantity of inertia possessed by an object.

• Mass creates gravity and, according to Galileo, all objects fall, despite their weight, fall at a constant speed.

• Note: Mass is NOT weight!

Consider this…

• You are the alien equivalent on an alien planet that is entering its Renaissance era.

• The planet is very similar to our own except it is exactly twice as massive. This is due to it having more heavy metals deep within its surface.

• The planet also possesses two moons. The first moon orbits at the same orbit as our moon. The second moon is twice as far away from the planet as the first.

• The orbit of the moons is also curious. One would assume that the moons fallow one another exactly. Or, in other words, they take the same amount of time to orbit.

• This, however, is NOT the case. The first moon, the moon that is as close to its home planet as our moon is to us, takes about 15 days to orbit its planet.

• The second moon takes about 1 month to orbit its planet like our moon does for us.

• This has confused your species, as the orbit time seems to exponentially decrease the further out the moon is.

Sooooo…

• As you are sitting under a meat tree, a slab of meat falls to the ground (twice as fast as it would on Earth). You realize, just as Newton did, that the force that pulled the slab of meat to the ground and the force keeping the moons in orbit and moving as fast as they do is the same force! In addition, you believe you can get the exact equation for this.

• After a few days of work, you come up with the EXACT equation for the gravity of your planet and how fast something falls to the surface.

Conclusion

• Those are Newton’s three laws and, as you can see, they are universal.

• Every molecule, every person, every planet, and every galaxy in the universe follows these same laws.