Does friction always oppose motion?Determining the direction of frictionFrictional forces apposing motionConsistent method for finding direction of static frictionHow does friction act on a body, if only 2 regions on it are rough?How to derive friction laws?Is this the correct way to think about why static friction is directed radially during a turn on a level surface?Motion of an object spiraling outwards on a rotating disk with frictionReliable, intuitive method for working out the direction of static friction?When does Rolling Friction come into play?Friction and Motion
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Does friction always oppose motion?
Determining the direction of frictionFrictional forces apposing motionConsistent method for finding direction of static frictionHow does friction act on a body, if only 2 regions on it are rough?How to derive friction laws?Is this the correct way to think about why static friction is directed radially during a turn on a level surface?Motion of an object spiraling outwards on a rotating disk with frictionReliable, intuitive method for working out the direction of static friction?When does Rolling Friction come into play?Friction and Motion
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$begingroup$
Recently I had the following misconceptions :
1) Static friction always opposes the motion of body.
2) The force of friction cannot initiate motion in a body.
Now I came to know that my understanding was wrong and that friction indeed can cause motion in bodies and that static friction does not always oppose the motion of a body.
But I found this quite bizarre, how can a force which has always been taught to us to oppose motion, oppose points 1) and 2)?
homework-and-exercises newtonian-mechanics newtonian-gravity friction
edited 3 hours ago
Mike
13k1 gold badge43 silver badges58 bronze badges
asked 8 hours ago
KartikKartik
91 bronze badge
New contributor
Kartik is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
|
show 3 more comments
$begingroup$
Recently I had the following misconceptions :
1) Static friction always opposes the motion of body.
2) The force of friction cannot initiate motion in a body.
Now I came to know that my understanding was wrong and that friction indeed can cause motion in bodies and that static friction does not always oppose the motion of a body.
But I found this quite bizarre, how can a force which has always been taught to us to oppose motion, oppose points 1) and 2)?
homework-and-exercises newtonian-mechanics newtonian-gravity friction
edited 3 hours ago
Mike
13k1 gold badge43 silver badges58 bronze badges
asked 8 hours ago
KartikKartik
91 bronze badge
New contributor
Kartik is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
$begingroup$
Do you have any examples?
$endgroup$
– Azzinoth
8 hours ago
$begingroup$
No, that's the problem! I was doing a question where these were given as options along with others and we had to choose the write one . On seeing the answer key 2) and 1) were not given as the answers thus meaning that their opposite statements are correct .@Azzinoth
$endgroup$
– Kartik
8 hours ago
$begingroup$
Force is always the change in motion, thus frictional forces also have to cause a change in motion. Indeed friction decellerates moving objects. I don't see how these two points wouldn't hold.
$endgroup$
– Swike
8 hours ago
$begingroup$
Yeah but can you give me examples where friction is in the direction of motion of a body or when friction causes motion in a body @Swike
$endgroup$
– Kartik
8 hours ago
1
$begingroup$
@Kartik A classic example of static friction leading to motion is a car tire on the road. When the tire spins to accelerate your car, there's no movement at the point of contact between the tires and the road; yet the car moves forward. Another example is walking; static friction allows you to push sideways against the ground to give your body movement while your feet stay in place. As mentioned in the answer, the important thing is that friction resists relative movement; but that resistance can still apply forces to bodies.
$endgroup$
– JMac
8 hours ago
|
show 3 more comments
$begingroup$
Recently I had the following misconceptions :
1) Static friction always opposes the motion of body.
2) The force of friction cannot initiate motion in a body.
Now I came to know that my understanding was wrong and that friction indeed can cause motion in bodies and that static friction does not always oppose the motion of a body.
But I found this quite bizarre, how can a force which has always been taught to us to oppose motion, oppose points 1) and 2)?
homework-and-exercises newtonian-mechanics newtonian-gravity friction
edited 3 hours ago
Mike
13k1 gold badge43 silver badges58 bronze badges
asked 8 hours ago
KartikKartik
91 bronze badge
New contributor
Kartik is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
Recently I had the following misconceptions :
1) Static friction always opposes the motion of body.
2) The force of friction cannot initiate motion in a body.
Now I came to know that my understanding was wrong and that friction indeed can cause motion in bodies and that static friction does not always oppose the motion of a body.
But I found this quite bizarre, how can a force which has always been taught to us to oppose motion, oppose points 1) and 2)?
homework-and-exercises newtonian-mechanics newtonian-gravity friction
homework-and-exercises newtonian-mechanics newtonian-gravity friction
edited 3 hours ago
Mike
13k1 gold badge43 silver badges58 bronze badges
asked 8 hours ago
KartikKartik
91 bronze badge
New contributor
Kartik is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 3 hours ago
Mike
13k1 gold badge43 silver badges58 bronze badges
asked 8 hours ago
KartikKartik
91 bronze badge
New contributor
Kartik is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 3 hours ago
Mike
13k1 gold badge43 silver badges58 bronze badges
edited 3 hours ago
Mike
13k1 gold badge43 silver badges58 bronze badges
edited 3 hours ago
Mike
13k1 gold badge43 silver badges58 bronze badges
13k1 gold badge43 silver badges58 bronze badges
asked 8 hours ago
KartikKartik
91 bronze badge
New contributor
Kartik is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 8 hours ago
KartikKartik
91 bronze badge
asked 8 hours ago
KartikKartik
91 bronze badge
91 bronze badge
New contributor
Kartik is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Kartik is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$begingroup$
Do you have any examples?
$endgroup$
– Azzinoth
8 hours ago
$begingroup$
No, that's the problem! I was doing a question where these were given as options along with others and we had to choose the write one . On seeing the answer key 2) and 1) were not given as the answers thus meaning that their opposite statements are correct .@Azzinoth
$endgroup$
– Kartik
8 hours ago
$begingroup$
Force is always the change in motion, thus frictional forces also have to cause a change in motion. Indeed friction decellerates moving objects. I don't see how these two points wouldn't hold.
$endgroup$
– Swike
8 hours ago
$begingroup$
Yeah but can you give me examples where friction is in the direction of motion of a body or when friction causes motion in a body @Swike
$endgroup$
– Kartik
8 hours ago
1
$begingroup$
@Kartik A classic example of static friction leading to motion is a car tire on the road. When the tire spins to accelerate your car, there's no movement at the point of contact between the tires and the road; yet the car moves forward. Another example is walking; static friction allows you to push sideways against the ground to give your body movement while your feet stay in place. As mentioned in the answer, the important thing is that friction resists relative movement; but that resistance can still apply forces to bodies.
$endgroup$
– JMac
8 hours ago
|
show 3 more comments
$begingroup$
Do you have any examples?
$endgroup$
– Azzinoth
8 hours ago
$begingroup$
No, that's the problem! I was doing a question where these were given as options along with others and we had to choose the write one . On seeing the answer key 2) and 1) were not given as the answers thus meaning that their opposite statements are correct .@Azzinoth
$endgroup$
– Kartik
8 hours ago
$begingroup$
Force is always the change in motion, thus frictional forces also have to cause a change in motion. Indeed friction decellerates moving objects. I don't see how these two points wouldn't hold.
$endgroup$
– Swike
8 hours ago
$begingroup$
Yeah but can you give me examples where friction is in the direction of motion of a body or when friction causes motion in a body @Swike
$endgroup$
– Kartik
8 hours ago
1
$begingroup$
@Kartik A classic example of static friction leading to motion is a car tire on the road. When the tire spins to accelerate your car, there's no movement at the point of contact between the tires and the road; yet the car moves forward. Another example is walking; static friction allows you to push sideways against the ground to give your body movement while your feet stay in place. As mentioned in the answer, the important thing is that friction resists relative movement; but that resistance can still apply forces to bodies.
$endgroup$
– JMac
8 hours ago
$begingroup$
Do you have any examples?
$endgroup$
– Azzinoth
8 hours ago
$begingroup$
Do you have any examples?
$endgroup$
– Azzinoth
8 hours ago
$begingroup$
No, that's the problem! I was doing a question where these were given as options along with others and we had to choose the write one . On seeing the answer key 2) and 1) were not given as the answers thus meaning that their opposite statements are correct .@Azzinoth
$endgroup$
– Kartik
8 hours ago
$begingroup$
No, that's the problem! I was doing a question where these were given as options along with others and we had to choose the write one . On seeing the answer key 2) and 1) were not given as the answers thus meaning that their opposite statements are correct .@Azzinoth
$endgroup$
– Kartik
8 hours ago
$begingroup$
Force is always the change in motion, thus frictional forces also have to cause a change in motion. Indeed friction decellerates moving objects. I don't see how these two points wouldn't hold.
$endgroup$
– Swike
8 hours ago
$begingroup$
Force is always the change in motion, thus frictional forces also have to cause a change in motion. Indeed friction decellerates moving objects. I don't see how these two points wouldn't hold.
$endgroup$
– Swike
8 hours ago
$begingroup$
Yeah but can you give me examples where friction is in the direction of motion of a body or when friction causes motion in a body @Swike
$endgroup$
– Kartik
8 hours ago
$begingroup$
Yeah but can you give me examples where friction is in the direction of motion of a body or when friction causes motion in a body @Swike
$endgroup$
– Kartik
8 hours ago
1
1
$begingroup$
@Kartik A classic example of static friction leading to motion is a car tire on the road. When the tire spins to accelerate your car, there's no movement at the point of contact between the tires and the road; yet the car moves forward. Another example is walking; static friction allows you to push sideways against the ground to give your body movement while your feet stay in place. As mentioned in the answer, the important thing is that friction resists relative movement; but that resistance can still apply forces to bodies.
$endgroup$
– JMac
8 hours ago
$begingroup$
@Kartik A classic example of static friction leading to motion is a car tire on the road. When the tire spins to accelerate your car, there's no movement at the point of contact between the tires and the road; yet the car moves forward. Another example is walking; static friction allows you to push sideways against the ground to give your body movement while your feet stay in place. As mentioned in the answer, the important thing is that friction resists relative movement; but that resistance can still apply forces to bodies.
$endgroup$
– JMac
8 hours ago
|
show 3 more comments
3 Answers
3
active
oldest
votes
$begingroup$
Friction opposes relative motion between two bodies.
Note that might mean that friction can create motion relative to i.e. you. For example, dropping an item on a moving belt. Friction opposes and reduces the relative motion of the item and belt until they move together. But now they’ve started moving relative to you.
answered 8 hours ago
Bob JacobsenBob Jacobsen
6,44110 silver badges22 bronze badges
$endgroup$
add a comment |
$begingroup$
Friction opposes the motion between THE TWO SURFACES IN CONTACT (the motion that would have happened if there was no friction). You can walk because the friction pushes the sole of your shoe forward. If there was no friction, the sole of the shoe would move backward (the direction you are kicking the Earth).
Whether those surfaces are in moving/rotating parts of a composite object is another story. Again, it is not about the relative motion of the bodies, but about the motion of the surfaces in contact. When the tires in your car are rotating, the point of contact of the tires against the road is pushing the road towards the back of the car. Without friction, the tires would spin in the same place. Because of friction, the tires push the road backward and, by the 3rd law, the road pushes the tires forward. That happens when you are speeding up. When you are slowing down, the point of contact of the tires with the road begin to push the road forward. Note that the car is still moving forward. That proves it is not about the relative motion of the bodies but about the motion of the surfaces (that would have happened if there was no friction). Ergo, the other answer is incorrect.
answered 7 hours ago
t_dt_d
656 bronze badges
$endgroup$
add a comment |
$begingroup$
Friction opposes relative motion ,for example suppose you have car why the car move forward although you just apply mechanical work only on wheel for circular motion ,reason is simple my friend friction when you see at lowest point of wheel which is touching the ground it moving in backward direction so friction applies himself in forward direction.where friction see that relative motion may happen friction apply himself to oppose it
answered 2 hours ago
yuvraj singhyuvraj singh
198 bronze badges
$endgroup$
add a comment |
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3 Answers
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3 Answers
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$begingroup$
Friction opposes relative motion between two bodies.
Note that might mean that friction can create motion relative to i.e. you. For example, dropping an item on a moving belt. Friction opposes and reduces the relative motion of the item and belt until they move together. But now they’ve started moving relative to you.
answered 8 hours ago
Bob JacobsenBob Jacobsen
6,44110 silver badges22 bronze badges
$endgroup$
add a comment |
$begingroup$
Friction opposes relative motion between two bodies.
Note that might mean that friction can create motion relative to i.e. you. For example, dropping an item on a moving belt. Friction opposes and reduces the relative motion of the item and belt until they move together. But now they’ve started moving relative to you.
answered 8 hours ago
Bob JacobsenBob Jacobsen
6,44110 silver badges22 bronze badges
$endgroup$
add a comment |
$begingroup$
Friction opposes relative motion between two bodies.
Note that might mean that friction can create motion relative to i.e. you. For example, dropping an item on a moving belt. Friction opposes and reduces the relative motion of the item and belt until they move together. But now they’ve started moving relative to you.
answered 8 hours ago
Bob JacobsenBob Jacobsen
6,44110 silver badges22 bronze badges
$endgroup$
Friction opposes relative motion between two bodies.
Note that might mean that friction can create motion relative to i.e. you. For example, dropping an item on a moving belt. Friction opposes and reduces the relative motion of the item and belt until they move together. But now they’ve started moving relative to you.
answered 8 hours ago
Bob JacobsenBob Jacobsen
6,44110 silver badges22 bronze badges
answered 8 hours ago
Bob JacobsenBob Jacobsen
6,44110 silver badges22 bronze badges
answered 8 hours ago
Bob JacobsenBob Jacobsen
6,44110 silver badges22 bronze badges
answered 8 hours ago
Bob JacobsenBob Jacobsen
6,44110 silver badges22 bronze badges
6,44110 silver badges22 bronze badges
add a comment |
add a comment |
$begingroup$
Friction opposes the motion between THE TWO SURFACES IN CONTACT (the motion that would have happened if there was no friction). You can walk because the friction pushes the sole of your shoe forward. If there was no friction, the sole of the shoe would move backward (the direction you are kicking the Earth).
Whether those surfaces are in moving/rotating parts of a composite object is another story. Again, it is not about the relative motion of the bodies, but about the motion of the surfaces in contact. When the tires in your car are rotating, the point of contact of the tires against the road is pushing the road towards the back of the car. Without friction, the tires would spin in the same place. Because of friction, the tires push the road backward and, by the 3rd law, the road pushes the tires forward. That happens when you are speeding up. When you are slowing down, the point of contact of the tires with the road begin to push the road forward. Note that the car is still moving forward. That proves it is not about the relative motion of the bodies but about the motion of the surfaces (that would have happened if there was no friction). Ergo, the other answer is incorrect.
answered 7 hours ago
t_dt_d
656 bronze badges
$endgroup$
add a comment |
$begingroup$
Friction opposes the motion between THE TWO SURFACES IN CONTACT (the motion that would have happened if there was no friction). You can walk because the friction pushes the sole of your shoe forward. If there was no friction, the sole of the shoe would move backward (the direction you are kicking the Earth).
Whether those surfaces are in moving/rotating parts of a composite object is another story. Again, it is not about the relative motion of the bodies, but about the motion of the surfaces in contact. When the tires in your car are rotating, the point of contact of the tires against the road is pushing the road towards the back of the car. Without friction, the tires would spin in the same place. Because of friction, the tires push the road backward and, by the 3rd law, the road pushes the tires forward. That happens when you are speeding up. When you are slowing down, the point of contact of the tires with the road begin to push the road forward. Note that the car is still moving forward. That proves it is not about the relative motion of the bodies but about the motion of the surfaces (that would have happened if there was no friction). Ergo, the other answer is incorrect.
answered 7 hours ago
t_dt_d
656 bronze badges
$endgroup$
add a comment |
$begingroup$
Friction opposes the motion between THE TWO SURFACES IN CONTACT (the motion that would have happened if there was no friction). You can walk because the friction pushes the sole of your shoe forward. If there was no friction, the sole of the shoe would move backward (the direction you are kicking the Earth).
Whether those surfaces are in moving/rotating parts of a composite object is another story. Again, it is not about the relative motion of the bodies, but about the motion of the surfaces in contact. When the tires in your car are rotating, the point of contact of the tires against the road is pushing the road towards the back of the car. Without friction, the tires would spin in the same place. Because of friction, the tires push the road backward and, by the 3rd law, the road pushes the tires forward. That happens when you are speeding up. When you are slowing down, the point of contact of the tires with the road begin to push the road forward. Note that the car is still moving forward. That proves it is not about the relative motion of the bodies but about the motion of the surfaces (that would have happened if there was no friction). Ergo, the other answer is incorrect.
answered 7 hours ago
t_dt_d
656 bronze badges
$endgroup$
Friction opposes the motion between THE TWO SURFACES IN CONTACT (the motion that would have happened if there was no friction). You can walk because the friction pushes the sole of your shoe forward. If there was no friction, the sole of the shoe would move backward (the direction you are kicking the Earth).
Whether those surfaces are in moving/rotating parts of a composite object is another story. Again, it is not about the relative motion of the bodies, but about the motion of the surfaces in contact. When the tires in your car are rotating, the point of contact of the tires against the road is pushing the road towards the back of the car. Without friction, the tires would spin in the same place. Because of friction, the tires push the road backward and, by the 3rd law, the road pushes the tires forward. That happens when you are speeding up. When you are slowing down, the point of contact of the tires with the road begin to push the road forward. Note that the car is still moving forward. That proves it is not about the relative motion of the bodies but about the motion of the surfaces (that would have happened if there was no friction). Ergo, the other answer is incorrect.
answered 7 hours ago
t_dt_d
656 bronze badges
edited 3 hours ago
answered 7 hours ago
t_dt_d
656 bronze badges
answered 7 hours ago
t_dt_d
656 bronze badges
answered 7 hours ago
t_dt_d
656 bronze badges
656 bronze badges
add a comment |
add a comment |
$begingroup$
Friction opposes relative motion ,for example suppose you have car why the car move forward although you just apply mechanical work only on wheel for circular motion ,reason is simple my friend friction when you see at lowest point of wheel which is touching the ground it moving in backward direction so friction applies himself in forward direction.where friction see that relative motion may happen friction apply himself to oppose it
answered 2 hours ago
yuvraj singhyuvraj singh
198 bronze badges
$endgroup$
add a comment |
$begingroup$
Friction opposes relative motion ,for example suppose you have car why the car move forward although you just apply mechanical work only on wheel for circular motion ,reason is simple my friend friction when you see at lowest point of wheel which is touching the ground it moving in backward direction so friction applies himself in forward direction.where friction see that relative motion may happen friction apply himself to oppose it
answered 2 hours ago
yuvraj singhyuvraj singh
198 bronze badges
$endgroup$
add a comment |
$begingroup$
Friction opposes relative motion ,for example suppose you have car why the car move forward although you just apply mechanical work only on wheel for circular motion ,reason is simple my friend friction when you see at lowest point of wheel which is touching the ground it moving in backward direction so friction applies himself in forward direction.where friction see that relative motion may happen friction apply himself to oppose it
answered 2 hours ago
yuvraj singhyuvraj singh
198 bronze badges
$endgroup$
Friction opposes relative motion ,for example suppose you have car why the car move forward although you just apply mechanical work only on wheel for circular motion ,reason is simple my friend friction when you see at lowest point of wheel which is touching the ground it moving in backward direction so friction applies himself in forward direction.where friction see that relative motion may happen friction apply himself to oppose it
answered 2 hours ago
yuvraj singhyuvraj singh
198 bronze badges
answered 2 hours ago
yuvraj singhyuvraj singh
198 bronze badges
answered 2 hours ago
yuvraj singhyuvraj singh
198 bronze badges
answered 2 hours ago
yuvraj singhyuvraj singh
198 bronze badges
198 bronze badges
add a comment |
add a comment |
Kartik is a new contributor. Be nice, and check out our Code of Conduct.
Kartik is a new contributor. Be nice, and check out our Code of Conduct.
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$begingroup$
Do you have any examples?
$endgroup$
– Azzinoth
8 hours ago
$begingroup$
No, that's the problem! I was doing a question where these were given as options along with others and we had to choose the write one . On seeing the answer key 2) and 1) were not given as the answers thus meaning that their opposite statements are correct .@Azzinoth
$endgroup$
– Kartik
8 hours ago
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Force is always the change in motion, thus frictional forces also have to cause a change in motion. Indeed friction decellerates moving objects. I don't see how these two points wouldn't hold.
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– Swike
8 hours ago
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Yeah but can you give me examples where friction is in the direction of motion of a body or when friction causes motion in a body @Swike
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– Kartik
8 hours ago
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@Kartik A classic example of static friction leading to motion is a car tire on the road. When the tire spins to accelerate your car, there's no movement at the point of contact between the tires and the road; yet the car moves forward. Another example is walking; static friction allows you to push sideways against the ground to give your body movement while your feet stay in place. As mentioned in the answer, the important thing is that friction resists relative movement; but that resistance can still apply forces to bodies.
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– JMac
8 hours ago