Issue with an aspect of moments and reactionary force

In summary, the conversation discusses finding the tension in a wire and the magnitude of the reaction force at a hinge in a problem involving a uniform rod and a 10kg mass. The person is struggling to find the correct reaction force and is asking for assistance before an upcoming exam. They have attempted to solve the problem but are unsure of their answer.
  • #1
Dongorgon
20
0
My main issue here is determining the correct reaction force, I'm truly lost as to where I'm making a mistake?
The question is: A uniform rod of length 2m and mass 5kg is connected to a vertical wall by a smooth hinge at A and a wire CB as shown. If a 10kg mass is attached to D, find:
The tension in the wire (Obvious, answered on the attachment)
The magnitude of the reaction in the hinge at A (truly stuck here!)

Am i correct in assuming the forces are in equilibrium and that the reactionary force would be perpendicular to the wall itself?

Any assistance/advice would be much appreciated, I have an exam tomorrow based around these concepts. Thanks.

The attachment is my attempt so far with the desired answer for the second part in red at the bottom:

hv18co.jpg
 
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  • #2
Check your value of tension. It seems to be wrong.

Regarding the normal reaction, the equation using moments seems to yield an answer of 686N but the force equation i.e. to balance the components of force along the length of the rod seems to yield that R=73.5 N, assuming that the rod is at rest. So I guess somewhere ( I don't know where) there's a mistake.
 

Related to Issue with an aspect of moments and reactionary force

What is a moment and how does it relate to reactionary force?

A moment is a measure of the tendency of a force to rotate an object around a specific point. It is calculated by multiplying the magnitude of the force by the perpendicular distance from the point to the line of action of the force. In terms of reactionary force, moments can cause an object to rotate if there is an imbalance of forces acting on it, resulting in a reactionary force to counteract the rotation.

What is the difference between a moment and a torque?

While both moments and torque involve the rotation of an object, torque specifically refers to the rotational force or effectiveness of a force in causing an object to rotate. Moments, on the other hand, can be calculated for any type of force, not just rotational ones.

How do you calculate the magnitude and direction of a moment?

The magnitude of a moment can be calculated by multiplying the magnitude of the force by the perpendicular distance from the point to the line of action of the force. The direction of the moment is perpendicular to both the line of action of the force and the line connecting the point to the line of action.

What are some common issues that can arise with moments and reactionary force?

One common issue is when the moment forces on an object are not in equilibrium, resulting in a reactionary force that causes the object to rotate. Another issue could be when the moment arm (perpendicular distance) is not accurately measured, leading to errors in calculating the moment.

How can we use moments and reactionary force to solve real-world problems?

Moments and reactionary force are commonly used in engineering and physics to analyze and design structures, machines, and other systems. By understanding the principles of moments and reactionary force, we can determine the stability and strength of structures and predict how they will behave under different loads and forces. This can help us solve real-world problems and make informed decisions in various industries.

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