Mechanics: could someone check my diagram please?

In summary, the end of the rod is hinged to a horizontal plane, and the end of the rod is in contact with a cylinder that is resting on the horizontal plane. There is a static frictional force between the rod and the cylinder, and a normal force of the floor on the rod at the point of contact.
  • #1
knowlewj01
110
0

Homework Statement



A uniform rod of length 2a and weight W rests at an angle of 60° to the horizontal with one end hinged to a horizontal plane and one end resting on a cylinder of radius a and weight W that is itself resting on the horizontal plane. The axis of the cylinder is perpendicular to the vertical plane containing the rod. The contacts between the rod and the cylinder and between the cylinder and the ground are rough. Find the ratio of the frictional force to the normal reaction force at the point of contact of: i) the cylinder with the plane and ii) the rod with the cylinder

Homework Equations





The Attempt at a Solution



I have uploaded my diagram, just wondering if i have all the forces there and the correct directions. Thanks
 

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  • #2
I think there should be a normal reaction from the plane on the rod but i can't decide wether it should be perpendicular to the plane or the rod. any ideas?
 
  • #3
Is this a dynamic or static problem? You show the cylinder rotating.

-The normal force of the cylinder on the rod should be at it's point of contact along a line passing through the center of the cylinder.

-The rod is hinged to the surface.

-The weight of the rod should pass through it's center.

-The frictional force between the rod and the cylinder is missing.
 
  • #4
the system is in equilibrium and in limiting friction such that
F=[tex]\mu[/tex]R

is the normal reaction of the rod on the floor perpendicular to the floor? i think this is right, then to solve the problem i should resolve and take moments.
 
  • #5
knowlewj01 said:
the system is in equilibrium and in limiting friction such that
F=[tex]\mu[/tex]R

is the normal reaction of the rod on the floor perpendicular to the floor? i think this is right, then to solve the problem i should resolve and take moments.

Yes it is. But I don't know what 'limiting friction' means.

There are two forces on the end of the rod. There is a vertical normal force of the floor on the rod at the point of contact, and a static frictional force directed in the negative x direction upon the end of the rod.
 
  • #6
But the question says one end is hinged to the horizontal. Doesn't that mean you count them as one object? (ie no normal force or friction)
 
  • #7
ChrisBaker8 said:
But the question says one end is hinged to the horizontal. Doesn't that mean you count them as one object? (ie no normal force or friction)

Yes, that's a better way of looking at it. The magntude and direction of the force at the hing is unknown. It has to be found as a result of the other forces.
 

1. What is Mechanics?

Mechanics is a branch of physics that deals with the study of motion, forces, and energy in physical systems. It is concerned with the behavior of objects under the influence of external forces and how they respond to these forces.

2. What is the purpose of a diagram in Mechanics?

A diagram in Mechanics is used to visually represent the physical system being studied. It helps to illustrate the relationships between the different components of the system and how they interact with each other.

3. How do I check if my Mechanics diagram is accurate?

To check if your Mechanics diagram is accurate, you can compare it to the principles and laws of Mechanics, such as Newton's Laws of Motion, and see if it accurately depicts the relationships and interactions between the components in your system.

4. Can someone else check my Mechanics diagram for me?

Yes, someone else who is knowledgeable in Mechanics can check your diagram for accuracy and provide feedback. It is always helpful to have a second set of eyes to catch any errors or inconsistencies in your diagram.

5. Are there any specific guidelines for creating a Mechanics diagram?

There are no strict guidelines for creating a Mechanics diagram, but it is important to label all the components and forces accurately, use appropriate symbols, and maintain consistency in the scale and direction of the vectors. It is also recommended to include a reference point and a coordinate axis for better understanding.

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