System of forces and torque on an object

• Rushers
In summary, the problem is trying to find a relationship between two vectors and there is no known relationship between them.
Rushers
http://imageshack.us/photo/my-images/121/helperw.png/

Have a look at this picture. It contains my problem.
I don't really know how to differentiate torques, momentums and forces.

I attempted to do as follows :

Get the moment of N ( N*e, with e being a unit vector pointing upwards)
Get the momentof F. (easy)
Get the moment of R . Here I don't understand if the R is related to the torque T or not so I don't know how to get it.

After getting all moments, I just apply the equilibrium principle.

Another problem I have is the forces. The object is in equilibirum but we have only one "real" force which acts upon the object which is gravity. Other forces are torques really.
So there must be a way of making "forces" out of torques or forces that tend to move the body around a pivot like F or N.

How would you do to solve this question?

This problem is very simple. You are given the vector quantities of all the forces and moments on the diagram except N. Have you tried writing equations of static equilibrium, since the object is stated to be in equilibrium? (Hint: use the pivot point as your reference)

I could of course write an expression of static equilibirum.

Sum of all moments is zero and sum of all forces is zero.

BUT

How can I transform N into a force? It is a momentum, not really a force.
And what is the realtionship between R and T?
And if T was a torque, why isn't it applied in the centre of gravity? and if so, is it possible to "shift" it to the centre of gravity?

Last edited:
There is no requirement for a torque to be applied only about the center of gravity of an object.

N is the normal force of the object resting on the roller. It is not a moment. (Note: momentum in English denotes the product of a mass and velocity. A moment is the product of a force and a distance)

R is an oblique force applied at the pin, with the components noted in the problem statement. T is a torque (or moment) coincidentally applied at the same location as R. There is no known relationship between R and T.

This is a very simple problem. You are trying to make it more complex than it truly is.

Can you check if possible?

Successed!

Thank you for your help mate !

My Mechanics exam is in two days.

What is a system of forces?

A system of forces refers to a group of forces acting on an object or a system of objects. These forces can be either balanced or unbalanced, and they can have different magnitudes and directions.

What is torque?

Torque is a measure of the rotational force acting on an object. It is calculated by multiplying the magnitude of the force by the distance between the force and the axis of rotation.

How do you calculate the net force on an object?

The net force on an object is calculated by adding all the individual forces acting on the object. If the net force is zero, the object will remain in a state of rest or constant velocity. If the net force is non-zero, the object will experience acceleration in the direction of the net force.

What is the center of mass?

The center of mass is the point at which the mass of an object is concentrated. It is the point where the object will balance in any orientation, and it is often used to simplify calculations involving the motion of an object.

How does the distribution of forces affect the torque on an object?

The distribution of forces can affect the torque on an object in two ways. First, the magnitude of the force can affect the torque, with larger forces producing larger torques. Second, the distance between the force and the axis of rotation can affect the torque, with larger distances producing larger torques. Therefore, a concentrated force applied further away from the axis of rotation will produce a larger torque than the same force applied closer to the axis of rotation.

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