Physics 4.7.3b - Friction Example 2

Example problem dealing with friction.

[derekowens]

@804YankeeFan Yes, you are correct. The difference is small, though, and is typically ignored for basic problems like the one in this example.

The earth is not doing work on us to keep us rotating. The earth continues to rotate (and we along with it) as long as there is no friction to stop it, and there basically is none. Think of it as rotational inertia. The rotational energy of the earth was there when the earth was formed, and it is still there.

[swervo]

These shorter videos bouta get more hype in this generation watchhh

[Monsterenergy]

Your videos deserve many more views than they have right now. Good job!

[derekowens]

@nabeel223903 Good question. And there is a very good answer: If the forces are balanced, that means that there is no acceleration. So the velocity will not change. If it is already moving, the fact that the forces are balanced means it will keep moving at a constant speed. There was, presumably, some larger force that got it moving from rest, but once it's moving, the total net force to keep it moving at a constant velocity will be zero.

[YankeeFan]

quick question as well, I thought the normal force should not really equal the weight because there need to be a centripetal acceleration to keep us rotating with the Earth. I learnt that in my physics class. And I have another question about the rotational of the earth. Is the earth doing work on us to keep us moving with the earth? Where do we get that rotational energy from?

[MonseFilomeno]

thank you soo much im a freshman taking physics and its so hard i have a D but i hope i get it up soon because i need it to play a sport but you helped me understand this a bit more

[ewaschenko]

Thank-you got this question in less than a minute :)

[nabeel]

quick question, if the fnet is 0, then how is the object moving at a velocity? if all forces are balanced, wont the object not move?