Question about Angular Motion in a horizontal plane

In summary, for finding the minimum speed for a mass to spin on the end of a taut string on a vertical plane, either the tension or the contact force should be taken as 0, equating to F=W. On a horizontal plane, the tension is equal to the centripetal force, allowing F=W to still be used to find the minimum speed. This is because the tension is responsible for keeping the mass in its circular motion, and equating it to the weight ensures that the minimum speed is high enough for the mass to maintain its orbit.
  • #1
sodnaz
For finding the critical speed or the minimum speed in a question for a vertical plane, you take either the friction or the contact (normal) force to be 0, so F=W

However, for a horizontal plane, like spinning something around in a circle, you can still do F=W to find the critical speed or the minimum speed. Why is this? I know that for a horizontal plane, the tension is equal to the centripetal force, but why can you still just equate F=W to find V that way, when tension is the centripetal force.
 
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  • #2
sodnaz said:
For finding the critical speed or the minimum speed in a question for a vertical plane, you take either the friction or the contact (normal) force to be 0, so F=W

However, for a horizontal plane, like spinning something around in a circle, you can still do F=W to find the critical speed or the minimum speed. Why is this? I know that for a horizontal plane, the tension is equal to the centripetal force, but why can you still just equate F=W to find V that way, when tension is the centripetal force.
Welcome to the PF. :smile:

Can you post a couple diagrams for what you are asking about? For the vertical case, it sounds like you are asking about the minimum speed to spin a mass on the end of taut string, but then you mention friction... And for the horizontal case, what do you mean by "critical speed"?
 
  • #3
berkeman said:
Welcome to the PF. :smile:

Can you post a couple diagrams for what you are asking about? For the vertical case, it sounds like you are asking about the minimum speed to spin a mass on the end of taut string, but then you mention friction... And for the horizontal case, what do you mean by "critical speed"?
Sorry, my mistake. For the vertical case, I meant to say tension and not friction. For the horizontal case, ignore where I said 'critical speed' and replace that with the minimum speed for the mass to spin on the end of a taut string again, so that it stays spinning and the velocity isn't small enough that it stops spinning and falls out of it's 'orbit' (so to speak)
 

Related to Question about Angular Motion in a horizontal plane

1. What is angular motion in a horizontal plane?

Angular motion in a horizontal plane refers to the movement of an object in a circular path on a flat surface, such as a wheel rolling on the ground. It involves both linear motion (movement along a straight line) and rotational motion (movement around a central axis).

2. What factors affect angular motion in a horizontal plane?

The factors that affect angular motion in a horizontal plane include the radius of the circular path, the speed of the object, and the force applied to the object. The mass and shape of the object may also play a role.

3. How is angular velocity calculated in horizontal motion?

Angular velocity is calculated by dividing the change in angular displacement by the change in time. It is typically measured in radians per second (rad/s) or degrees per second (deg/s).

4. Does the direction of angular motion in a horizontal plane matter?

Yes, the direction of angular motion in a horizontal plane matters. It is determined by the direction of the force causing the rotation and can be either clockwise or counterclockwise.

5. How does angular motion in a horizontal plane relate to linear motion?

Angular motion in a horizontal plane and linear motion are closely related. The linear velocity of an object can be calculated by multiplying the angular velocity by the radius of the circular path. Additionally, changes in linear velocity will result in corresponding changes in angular velocity and vice versa.

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