Direction of forces (centripetal/friction/tension)

[dnt]

my general question is how do you know what direction these forces point in, particularly when spinning an object on a string (either horizontally or vertically) or when say a car is driving in a circle.

the first one has centripetal acceleration and tension. the 2nd example has centripetal acceleration and friction.

how do you know what direction they point in? my guess is centripetal points in and the other two (friction/tension) point out but I am not sure. can someone please help? thanks.

 

[Astronuc]

http://hyperphysics.phy-astr.gsu.edu/hbase/cf.html

http://hyperphysics.phy-astr.gsu.edu/hbase/corf.html#cent

A string on a relvolving mass applies centripetal force and as a result it experiences tension (pulling force).

http://hyperphysics.phy-astr.gsu.edu/hbase/newt.html#strmas

Friction acts opposite the direction of motion.

 

[kyle8921]

I can provide an explanation for the direction of forces in these situations. Let's start with the first example of spinning an object on a string. This situation involves two forces - the tension force from the string and the centripetal force, which is directed towards the center of the circular motion. The tension force is what keeps the object moving in a circular path, while the centripetal force is what causes the object to accelerate towards the center.

Now, in terms of direction, you are correct in saying that the centripetal force points towards the center of the circle. This is because the object is constantly changing direction as it spins, and the centripetal force is responsible for this change in direction. On the other hand, the tension force from the string points away from the center, in the opposite direction of the centripetal force. This is because the string is pulling on the object, trying to keep it moving in a straight line, while the centripetal force is pulling it towards the center.

Moving on to the second example of a car driving in a circle, we have similar forces at play - the centripetal force and friction force. The centripetal force is still responsible for the car's change in direction, while the friction force is what allows the car to maintain traction on the road and not slide out of the circular path.

In terms of direction, once again, the centripetal force points towards the center of the circle, while the friction force points in the opposite direction, outwards from the center. This is because the friction force is trying to prevent the car from sliding outwards, while the centripetal force is pulling it towards the center.

In summary, the direction of forces in circular motion can be determined by understanding their roles in causing and maintaining the circular motion. The centripetal force will always point towards the center, while the other forces, such as tension and friction, will point in the opposite direction, trying to prevent the object from moving away from the center. I hope this helps clarify the concept for you.