How Do You Calculate Forces on a Plank with Unevenly Placed Weights?

In summary, the problem involves a uniform plank with a weight of 120 N resting on two stools. A weight of 80 N is placed on the plank, and the forces acting on each stool at points A and B are to be calculated. Using the equation for turning effect, the calculated forces are 88 N and 112 N respectively.
  • #1
psychicgerm
4
0
Moment -- A weight on a plank

Homework Statement



A uniform plank of weight 120 N rests on two stools as shown in the link provided below. A weight of 80N is placed on the plank, midway between the stools. Calculate the force acting on the stool at A and B. The answer is 80N and 120 N respectively. I calculated the answers to 88N and 112N.

The image link : http://imageshack.us/photo/my-images/864/moments.png/


Homework Equations



Turning effect = Force * Distance from the pivot

The Attempt at a Solution



(80*1.25) + (120*1.5) = FB * 2.5
FB = 112N

(80*1.25) + (120*1.0) = FA * 2.5
FA = 88N
 
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  • #2
welcome to pf!

hi psychicgerm! welcome to pf! :smile:
psychicgerm said:
(80*1.25) + (120*1.5) = FB * 2.5
FB = 112N

(80*1.25) + (120*1.0) = FA * 2.5
FA = 88N

it isn't 1.25 :wink:
 

FAQ: How Do You Calculate Forces on a Plank with Unevenly Placed Weights?

What is a moment in physics?

A moment in physics refers to the turning effect of a force on an object. It is calculated by multiplying the magnitude of the force by the perpendicular distance from the pivot point to the line of action of the force.

How is a moment different from a force?

A force is a push or pull on an object, while a moment refers to the turning effect of that force. A moment takes into account the distance from the pivot point, while a force does not.

How does a weight on a plank create a moment?

A weight on a plank creates a moment by exerting a force on the plank that causes it to rotate around a pivot point. The longer the distance between the weight and the pivot point, the greater the moment.

What is the equation for calculating moment?

The equation for calculating moment is M = Fd, where M is the moment, F is the force, and d is the perpendicular distance from the pivot point to the line of action of the force.

How can moments be used in real-world applications?

Moments are used in a variety of real-world applications, such as balancing objects, opening doors, and building structures. They are also important in understanding the stability and equilibrium of objects and systems.

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