00:01
Hello, in this video i'll be going over how to solve this problem involving the change in acceleration to do gravity when you go inside the earth.
00:08
So let's start with the same thing as before.
00:11
We have the law of universal gravitation equals to newton's second law is the same force acting on the same force of earth's gravity acting on the earth's object and we get acceleration equals this.
00:27
And on earth's surface we have g equals this where we plug in our capital r for radius of the earth and we want to find the acceleration when we're at a point 3r below the surface of the earth which is 0 .7r from the center of the earth so one thing that's tricky about is that when you actually go inside the earth the there's only like the small there's less mass of the earth there's yeah there's like because you have earth is a sphere and if you're at a point here only the mass like inside the like between the center of the earth and the your point will actually contribute to the force pulling, making the acceleration to gravity, and like the outer mass doesn't.
01:49
So, i assume that the earth has uniform density, and it's a perfect speed.
01:55
And, okay, we don't, we, and here i just use the equation for us here.
02:01
So we have mass is proportional to volume, so which is proportional to the radius cube.
02:08
And, okay, you know what? screw this.
02:13
There's a much better way to do the proportions...