Calculating Moments: Forces on a Ratchet Wrench

In summary, the problem involves two 20 lb forces applied to a ratchet wrench at points A and B to loosen bolt β. The task is to find the sum of the moments of these two forces about the x-axis of the bolt. The conversation also discusses how to find the moments at points A, B, and Q, and how to approach the problem with different pivots and angles. Ultimately, the solution involves finding the moment on the 8" wrench extension and projecting it onto the x-axis using cos(45).
  • #1
MienTommy
22
0

Homework Statement


Two 20 lb forces are applied to a ratchet wrench down at A and up at B to loosen bolt β. Find the sum of the moments of the two forces about the axis (x) of the bolt.

Homework Equations


What are the moments at point A, B, and Q?
How do I find the moment about the x-axis and not at the bolt β?

The Attempt at a Solution


Not sure how to set up the problem because of the different pivots Q and B which are angled.
hw1.png
 
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  • #2
First step: What torque is transmitted down the 8" wrench extension?
Have you studied torques as vectors?
 
  • #3
Yes I believe I have, but we call them moments? Could I just find the moment on the 8" wrench extension and project it on the x-axis by multiplying it by cos(45) to find the answer?
 
  • #4
Yes, I believe that's right.
 
  • #5
This is my attempt at the problem, I feel like it is wrong because of my Force vector.
 

Attachments

  • 20150907_205826.jpg
    20150907_205826.jpg
    14.4 KB · Views: 433
  • #6
Unfortunately, I can open, but can't read your attachment. What is the moment in the wrench extension?
 

FAQ: Calculating Moments: Forces on a Ratchet Wrench

What is a moment about an axis?

A moment about an axis is a measurement of the rotational force applied to an object around a specific axis or point. It is also referred to as torque.

How is a moment about an axis calculated?

The moment about an axis can be calculated using the formula: M = F * d, where M is the moment, F is the force applied, and d is the perpendicular distance from the axis to the line of action of the force.

What are the units of a moment about an axis?

The units of a moment about an axis are typically expressed in Newton-meters (Nm) or foot-pounds (ft-lbs), depending on the unit system being used.

What is the importance of calculating moments about an axis?

Calculating moments about an axis is important in the field of statics as it helps determine the stability and equilibrium of a structure or object. It is also used in engineering applications to analyze the strength and stress on various components.

How does the direction of a moment about an axis affect its magnitude?

The direction of a moment about an axis affects its magnitude because it is a vector quantity. This means that the direction of the force and the direction of the perpendicular distance from the axis to the line of action of the force must be taken into account when calculating the moment.

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