Wzory kinematyczne ruchu obrotowego. O nas. Transkrypcja. David explains the. mechanika dział fizyki zajmujący się ruchem, równowagą i oddziaływaniem ciał. mechanika klasyczna opiera się na trzech zasadach dynamiki newtona i bada. w opisie kinematyki oraz dynamiki ukła- dów korbowo-tłokowych . KINEMATYKA UKŁADU KORBOWO- jest od kąta α i dane jest wzorem (3), (5). The shift of.
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So this r, let’s be careful, this is always from the kindmatyka. These are the four kinematic formulas that relate the linear motion variables. That means that five revolutions would be five times two pi radians, which gives us 10 pi radians. Which variable isn’t involved? Well this thing slowed down to a stop. You ended wzlry with seconds squared on the top. So to find the speed we wsory just say that that’s equal to four meters, since you wanna know the speed of a point out here that’s four meters from the axis, and we multiply by the angular velocity, which initially was 40 radians per second.
If this bar would have slowed down, we’d of had to make sure that this alpha has the opposite sign as our angular velocity. It tells us this 30 radians per second squared. Well, since this object is speeding up, it started from rest, that means it sped up.
That’s our third known variable. So this time wzlry know omega initial 40 radians per second. They’re only true if the angular acceleration is constant.
Let’s do another one. So we know that alpha is 30 radians per second squared. That’s 40 radians per second squared. We multiply both side by two.
So we’ve got our angular displacement, what else do we know? But remember this only works, these equations only work if the acceleration is constant. So let me get rid of all this and let’s tackle this problem. So in other words, instead of V, the velocity, the final velocity, I would have omega, the final angular velocity. But that’s only two rotational kinematic variables.
So it’s gonna be 20 revolution times two pi radians per revolution. So that means that the area under the curve on a omega versus time graph, an angular velocity versus time graph is gonna represent the angular displacement. Now this second part, part b, says what kinematyks the angular velocity after rotating for five revolutions? Now there’s a couple ways we could solve this. You identify the variables that you know. They’re all rotating with the same number of radians per second, but the actual distance of the circle they’re traveling through is different, which makes all of their wzzory different.
We’ll bring these back, put ’em over here.
So recapping, these are the rotational kinematic formulas that relate the rotational kinematic variables. So let’s right those down. Transkrypcja filmu video – [Instructor] So in the previous couple videos, we defined all these new rotational motion variables and we defined them exactly the same way we defined all these linear motion variables.
And the closer in you go, the smaller the r will be, the smaller the speed will be. So we get rid of all that.
Powtórzenie wiadomości z kinematyki by Michał Sadownik on Prezi
So it said that it revolved five revolutions, that’s the amount of angle that it’s gone through, but it’s in weird units. And let’s tackle a couple examples of rotational kinematic formula problems. We don’t know alpha, but that’s what we wanna find, so I’m gonna leave that as a variable. If you were gonna ask what the speed of the rod would be halfway, that would be half as much.
You can write the radian, you can leave it off.
Wzory kinematyczne ruchu obrotowego
It’s gonna be when the alpha, the angular acceleration is constant. So this angular acceleration has gotta have the opposite sign to the initial angular velocity.
I don’t wanna use that one cause I wouldn’t know what to plug in here and I don’t wanna solve for it anyway.
Wzory kinematyczne ruchu obrotowego. And in fact, you use these, the exact same way you used these regular kinematic formulas.
Moment siły i moment pędu
That’s not the second or the third, it’s actually the fourth. Let’s check this one out. Again the way you use these, you identify what you know. Which one do we want to solve for?
So there they are. And in this case this is the axis right there.