How to choose the angle for inclined plane problems

In physics, sometimes the best way to make a problem simpler is to change the coordinate plane. Learn why the angle

Proving the angle for inclined planes

Confused on where to put the angle on inclined plane problems? Don't feel like memorizing it? Let's prove this using three basic principles from geometry:
A straight line is 180º
A triangle has a total of 180º
A right angle is 90º

From the last video we learned that rotating the coordinate axis could save us time and effort. But when doing it, we need to brake up the force of gravity into parts parallel and perpendicular to the surface. Notice how I draw the perpendicular part of gravity following right below the normal force. Anything perpendicular to the surface is a right angle, or 90º.

Did you notice how long arrow is for the force of gravity? I've made it longer this time so you can see how it forms a right angle with the with the base of the slope.

Now, all the angles in a triangle must add to 180º. This means that the angle on the top of the slop must be 60º.

Let's make an arc that reminds us that a line is 180º.

So if one point of the line to the other is 180º, and we know that 90º and 60º are taken care of, we are only missing what's left. So we take 180º-90º-60º and get 30º.

And that is why we use can use the angle of the slope in our similar triangle.

[ANATOMYTAJ]

you solved my three months long was continuously thinking about that..Thank you and very great vedeo

[HappyTunas]

FINALLY!!! This is the part that I couldn't understand from these problems and I didn't even know how to ask for help because I didn't know what "I didn't know" (meaning I didn't know what I didn't understand, I just knew it had to do with the trigonometric part of the problem).

Physics is easy. Trigonometry is hard... Thank you!!! :)

[user]

Very well explained. No idea why every explanation seems to skip over this!

[MubuReborn]

Nice video, illustrations were on point and explanation was clear. Thanks for this!

[sh]

Thank you so so much. This is honestly the clearest and simplest explanation I've found

[raydot-mo]

I like this explanation the best. It's very intuitive compared to others.

[MSSAKProductions]

Fabulous, just what I was looking for :)

[milkcreightronny]

thankyouthankyouthankyou I honestly cannot believe I got so lucky as to stumble across this video

[zyro]

I feel so happy. I was handicapped without this.

[rahul]

Thank you very much.. I've been wondering for the past hour how the angle of inclination can be resolved.. this helped me a lot.Thank you.!

[siddhantbhadsavale]

You are awesome sir..just one suggestion if You feel right..while explaining the part after 60 degrees plz mark 180 degree on grey side so that there will be less ambiguity
PS:-You saved the day sir.Thank you very much

[venkateshchavva]

Really superb explanation.
thanks to you brother.

[JullianaKeiSPino]

Thank you very much! this helped me a lot.

[nihaafzal]

thanku .... ur amazing :'''))

[gariden]

thank you. i'm taking a first year uni physics class as an elective but i'm not a first year and i don't remember a lot of the maths they assume i know from doing it the prior year in high school, lol. i didn't know how to find that angle.

[seggyRK]

Just what I was looking for! Thank you so much!

[IsmatunNissa]

THANK YOU SO MUCH FOR THIS!
I've been struggling with this for so long. If get an A, I'm dedicating it to you lol.

[ezramiller]

Very clear explanation! thank you so much!

[Sebkarp]

Thanks, I always wondered why theta was attributed to that angle in the small triangle and not the bottom one.

[greg]

30 was the single most obvious angle and it was clearly written as the slope. How did you derive the 60 degree angle without using the 30 degree angle?