Physics 8.1.03a - The Inverse Square Law

The nature of an inverse square law, and how it arises naturally as a property of three dimensional space. Newton understood geometrically that light dispersed according to an inverse square law and surmised, correctly, that gravitational force would be described in a similar manner. From the Physics course by Derek Owens.

Category:

Education

Tags:

• Physics
• gravity
• gravitation
• newton
• Isaac Newton
• gravitational force
• law of gravity
• universal gravitation
• inverse square
• inverse square law
• homeschool
• distance learning
• Derek Owens

[metalupyourass9]

I have a question, which is the only thing about this i dont quite understand. do u have to start at one metre? what if you start at 1.5, double that and at 3 metres away you have 4x the size (1/4 the light). but at that same point. (if you started ay 1 metre away) you would have 9x the original. or would that just be because your squares are smaller then, starting closer

[derekowens]

@metalupyourass9 Yes, I think you have the right idea. At 3 meters, you have 1/4 the light intensity that you have at 1.5 meters. Increasing the distance by a factor of 2 will cut the intensity to 1/4. And yes, if you start at 1 meter, then the squares you are imagining are smaller than if you start at 1.5 meters. At 3m, you will have 1/9 the light that you have at 1m, and 1/4 the light you have at 1.5m.

[presbarkeep]

awesome... good job, good video. easy to understand.

do sound waves follow the inverse square law too?

[derekowens]

Yes, I believe they do. Anything that propagates in three dimensions should follow an inverse square law.

[derekowens]

For gravity, it is F = (G m1 m2) / r^2.

For other inverse square relationships there are different equations, but they all have a similar form, that is, they all have a variable squared in the deonominator.

[deeppurple28]

Awesome vid!

[BrbWinning]

This video has given me such a better understanding of the entire concept. Thankyou very much!!!

[caaalsmith]

hi



[baden300]

thanks, really helped.



[wiccanXexodus]

@bomberfun1 you would have to take into account that light is absorbed and reflected off the air particles.

[NitromeSupporter]

you rock!

[natbienvenue310]

Not sure a laser follows the same law. It doesnt spread, or spreads very little

[nickdaleshockley]

Great job, what software did you use to make this live presentation if i might ask.