(Conceptual- Planar Kinetics) How to maintain the position

In summary, the conversation discusses whether a certain approach is correct and whether the friction force should be considered. It is proposed to use a combined center of mass for the bike and rider, with the actual location being near the rider's knees. The contact patch of the front tire is considered a fulcrum, with a horizontal friction force vector acting against the front brake. There is also a discussion about two moments in perfect balance, one clockwise and one counter-clockwise, induced by the weight and distance between the center of mass and contact patch.
  • #1
daphnelee-mh
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Homework Statement
attached below
Relevant Equations
attached below
Relevant equations :
1594783806206.png

1594783860244.png

Kindly advise whether this approach is correct, I am not sure whether the friction force should be considered.
 
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  • #2
You can consider a combined center of mass, rather than one for bike and one for rider.
The actual location of that CM is more or less by the knees of the rider.
The contact patch of the front tire can be considered a fulcrum.
The front brake is working, the bike is deccelerating and there is a horizontal friction force vector at the contact patch, pointing rearwards.

For a short period of time, there are two moments in perfect balance (zero angular velocity):
1) One is clockwise and is induced by the vector weight times horizontal distance between CM and contact patch.
2) The second one is counter-clockcwise and is induced by...

Stoppie_help3.png


tumblr_pnhs82Sftp1rjgjc7o1_500.gif
 
Last edited:

1. What is the concept of planar kinetics?

The concept of planar kinetics is the study of the motion of objects in a two-dimensional plane. It involves analyzing the forces acting on an object and how those forces affect its position, velocity, and acceleration.

2. What is the difference between position and displacement?

Position refers to the location of an object in a specific coordinate system, while displacement is the change in position of an object from its initial position to its final position. Displacement takes into account both the magnitude and direction of the change in position.

3. How can I maintain the position of an object?

To maintain the position of an object, you need to ensure that the net force acting on the object is zero. This means that all the forces acting on the object must be balanced, and there is no acceleration. This can be achieved by adjusting the magnitude and direction of the forces acting on the object.

4. What is the role of inertia in maintaining position?

Inertia is the tendency of an object to resist changes in its state of motion. In terms of maintaining position, inertia plays a role in keeping an object at rest or in motion with a constant velocity when there are no external forces acting on it. This means that if an object is already at rest, it will remain at rest unless acted upon by an external force.

5. How does friction affect the maintenance of position?

Friction is a force that opposes the motion of an object. In terms of maintaining position, friction can either help or hinder the process. If an object is already in motion, friction can help maintain its position by providing a force in the opposite direction. However, if an object is at rest, friction can make it more difficult to maintain its position as it creates a resistance to motion.

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