# Resultant and Moment Homework: Determine R & Moment about O

• LMW - Dk
In summary, the conversation is about determining the resultant force and moment about point O using given images and equations. One person has attempted to solve the problem and another has pointed out an error in their approach. The correct method is then explained and suggested to be used.
LMW - Dk

## Homework Statement

I have to determine the resultant R and the moment about O.

see the image.

## The Attempt at a Solution

See the image.

#### Attachments

• statics.PNG
39.4 KB · Views: 392
• Udklip 1.PNG
21.5 KB · Views: 428
• Udklip.PNG
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Hi LMW - Dk! Welcome to PF!

Show us what you've tried and where you're stuck, and then we'll know how to help!

See the pictures. I have found the moment and the resultant. However I think it's the wrong method ^^

sorry, i didn't notice your third picture

your Fz36 should be minus 36, shouldn't it?

(btw, i think most people find it easier to use cos and sin, of angles < 90°, and then use common-sense to decide whether its + or -)

i don't understand what you did to find the moment
can you please type it out in the post?​

Well can't you tell me how you would do this problem? how would you find the resultant and the moment?

If you click on the second picture then you can see that i have drawn a direction vector. Then i have found the cfross product of the direction vector and the resultant force.

LMW - Dk said:
If you click on the second picture then you can see that i have drawn a direction vector. Then i have found the cfross product of the direction vector and the resultant force.

ah, now i understand …

no, you've crossed the resultant with the position vector for only one of the vectors: you need to cross each vector with its own position vector, and then add (ie, there's no short-cut)

(and did the minus 36 help?)​

## 1. What is a resultant?

A resultant is the single force that has the same effect on an object as all the individual forces acting on the object combined. It is represented by an arrow pointing in the direction of the net force and its length represents the magnitude of the net force.

## 2. How do you calculate the resultant?

The resultant can be calculated by using the Pythagorean theorem, where the square of the resultant is equal to the sum of the squares of the individual forces. Alternatively, you can use vector addition, where you add the individual forces together and find the magnitude and direction of the resultant.

## 3. What is a moment?

A moment is the turning effect of a force about a point, also known as the torque. 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.

## 4. How do you determine the moment about a point?

To determine the moment about a point, you need to multiply the magnitude of the force by the perpendicular distance from the point to the line of action of the force. The unit for moment is Newton-meters (Nm).

## 5. What is the significance of calculating the resultant and moment?

Calculating the resultant and moment is important because it allows us to determine the overall effect of multiple forces acting on an object, as well as the turning effect of a force. This information is crucial in understanding the stability and movement of objects and structures in various situations.

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