anonymous
  • anonymous
At what direction is the frictional force?
Physics
schrodinger
  • schrodinger
See more answers at brainly.com
At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat.

Get this expert

answer on brainly

SEE EXPERT ANSWER

Get your free account and access expert answers to this
and thousands of other questions

anonymous
  • anonymous
1 Attachment
BTaylor
  • BTaylor
The frictional force is parallel to the surface, opposing the motion. So, it would be pointing down the slope, if the drawing in the arrow represents the motion.
anonymous
  • anonymous
Yes, the arrow represent the motion. But ummm, i'm not sure the frictional force is parallel to the surface, opposing the motion. Just like when we walk, the frictional force is in the same direction as our motion....

Looking for something else?

Not the answer you are looking for? Search for more explanations.

More answers

BTaylor
  • BTaylor
No, it's not. The friction always opposes motion.
anonymous
  • anonymous
|dw:1348327921150:dw|
anonymous
  • anonymous
|dw:1348328024524:dw|
BTaylor
  • BTaylor
the friction force reduces the acceleration of the object. When you are walking, the friction between your shoe/foot and the ground keeps your foot from sliding forward indefinitely.
anonymous
  • anonymous
|dw:1348328081329:dw|
anonymous
  • anonymous
@BTaylor yes, it oppose the motion, but the motion of our shoes.
anonymous
  • anonymous
the a point is moving in rotation direction so frictions force oppose it
anonymous
  • anonymous
that's why the car can rise rump
anonymous
  • anonymous
get @imron07 ?
anonymous
  • anonymous
@RaphaelFilgueiras : What about this:
1 Attachment
anonymous
  • anonymous
im talking about this
anonymous
  • anonymous
|dw:1348328369452:dw|
anonymous
  • anonymous
|dw:1348328561760:dw|
anonymous
  • anonymous
the friction is opposite to the moviment of weel
anonymous
  • anonymous
|dw:1348328592225:dw|
anonymous
  • anonymous
Yeah, i understand your explanation. But if we apply Newton's law, should we pick that direction too for friction to find system acceleration?
anonymous
  • anonymous
the friction is opposite to the moviment of POINT OF CONTACT
anonymous
  • anonymous
yep
anonymous
  • anonymous
Yes ma = mgsin alpha + f
anonymous
  • anonymous
f-mgsin(alpa)=ma
anonymous
  • anonymous
Shouldn't \(mg\sin{\alpha}\) is in opposite direction with friction now?
anonymous
  • anonymous
yes it is opposite
anonymous
  • anonymous
@RaphaelFilgueiras yes that's what I mean :)
anonymous
  • anonymous
NO it is coincident with mg sin alpha : here is why (let me finish pls
anonymous
  • anonymous
T|dw:1348328885247:dw|
anonymous
  • anonymous
And when wheel is freely rolling the friction acts BACK on it
anonymous
  • anonymous
so your car never will rise the ramp!!!
anonymous
  • anonymous
@RaphaelFilgueiras you are wrong : in his picture there are NO OTHER forces. The cart is only rolling up BY INERTIA and of course slows eventually. This is different from motorized climbing up !!!
anonymous
  • anonymous
the car is moving up
anonymous
  • anonymous
The point of contact is moving a wee-bit slower than the surface - so the surface ACCELERATES it !
anonymous
  • anonymous
@Mikael : So only when the engine turned on, friction will directed upward?
anonymous
  • anonymous
YES @imron07
anonymous
  • anonymous
And pls medal (-s)
anonymous
  • anonymous
the vector is velocity. And please admit that I am right @RaphaelFilgueiras
anonymous
  • anonymous
Again I clarify : When the wheel is free it serves as a friction-conduit from the surface to cart. When the motor is working the opposite: the wheel transfers torque from cart to surface
anonymous
  • anonymous
It is a delicate but DRAMATIC CHANGE
anonymous
  • anonymous
Well, i understand both of your opinion. But i agree with @Mikael . If the vector I draw is Force, would something change (engine on)?
anonymous
  • anonymous
Of course - all is opposite
anonymous
  • anonymous
they are opposite but mg is greater than f
anonymous
  • anonymous
so it will stop,and then the friction and mg will be in same direction
anonymous
  • anonymous
This time @RaphaelFilgueiras IS ok. Though he will never admit someone else IS .....
anonymous
  • anonymous
The last remark of Raf is WRONG (again!)_
anonymous
  • anonymous
You mean friction is downward even if the tire's working to move the car upward too?
anonymous
  • anonymous
Friction is UPWARD when the tire PUSHES the surface (working) and downward when the SURFACE pushes the tire
anonymous
  • anonymous
Both of you should imagine a tiny (really tiny) velocity difference betwee Contact point and surface. It has OPPOSITE directions in these opposite cases !
anonymous
  • anonymous
@Mikael can you draw it please, (when engine turned on, and another force pull the car too).
anonymous
  • anonymous
When wheel PUSHES it is faster downward - so frict is UPWARD
anonymous
  • anonymous
|dw:1348329423502:dw|
anonymous
  • anonymous
|dw:1348329805336:dw|
anonymous
  • anonymous
Okay, I understand now. Thanks @RaphaelFilgueiras & @Mikael !
anonymous
  • anonymous
yw
anonymous
  • anonymous
You see the friction force is OPPOSITE to the RELATIVE VELOCITY\[V_{contact} - V_{\text{surface velocity relative \to wheel's center}}\]
anonymous
  • anonymous
Yeah, that's what in my mind :D
anonymous
  • anonymous
@imron07 and @RaphaelFilgueiras : Thank you both for educating me and all of us by your questions and thoughts.
anonymous
  • anonymous
It was a nice discussion :)
anonymous
  • anonymous
DUBITANDO AD VERITATEM PERVENIMUS !
anonymous
  • anonymous
Veritas in disputando gignitur.
anonymous
  • anonymous
What's that last phrase means?
anonymous
  • anonymous
http://translate.google.com/#la/en/Veritas%20in%20disputando%20gignitur.
anonymous
  • anonymous
http://translate.google.com/#la/en/PERVENIMUS%20DUBITANDO%20AD%20VERITATEM
anonymous
  • anonymous
|dw:1348331561351:dw|
anonymous
  • anonymous
@experimentX
anonymous
  • anonymous
@RaphaelFilgueiras : can you explain more about your pic please?
anonymous
  • anonymous
forget the plane|dw:1348332081044:dw|
anonymous
  • anonymous
Okay, agree, then
anonymous
  • anonymous
|dw:1348332372621:dw|
anonymous
  • anonymous
the direction of friction is always in the moviment direction
anonymous
  • anonymous
in this case
anonymous
  • anonymous
Yes, please continue
anonymous
  • anonymous
so in your picture f is in direction of moviment
anonymous
  • anonymous
You mean my first, or second picture (or both)?
anonymous
  • anonymous
get it?
anonymous
  • anonymous
just matter the direction of moviment
anonymous
  • anonymous
Mmm, still thinking. For the first picture, it makes sense. But for the seecond (where another force pull the car)?
anonymous
  • anonymous
no matter the friction is always in direction of moviment
anonymous
  • anonymous
What disturb me: when we calculate the car's acceleration, ma=F+f-mg*sin(theta) It seems friction 'helps' F to push the car up.