Finding the perpendicular distance in this moments question

[Bolter]

Homework Statement

See below

Relevant Equations

moment = force x perp dist

I have tried this question but can't get my head around to doing part b)

This is the sketch I have drawn and I'm guessing 'x' is the distance that I have to fine that's perpendicular to force Fb, though I'm not sure if I have set it up correctly?

Any help would be appreciated! Thanks

 

[Chestermiller]

Extend the dotted line of FB down and to the left. Drop a normal to this line starting at point A. Determine the length of this normal line.

 

[Lnewqban]

Distance "x" of your drawing is not the one required to find.

Also, note that the angles of section AC and force Fb are the same.
A 45-degree inclined distance of 2 m separates both lines.
A perpendicular distance between those lines would be...

 

[Bolter]

Extend the dotted line of FB down and to the left. Drop a normal to this line starting at point A. Determine the length of this normal line.

Distance "x" of your drawing is not the one required to find.

Also, note that the angles of section AC and force Fb are the same.
A 45-degree inclined distance of 2 m separates both lines.
A perpendicular distance between those lines would be...

I redrew the diagram and and labelled the new perpendicular distance I have to find, however I don't think I have enough info in the question to be able to work out this distance unless I'm missing something?

 

[haruspex]

I redrew the diagram and and labelled the new perpendicular distance I have to find, however I don't think I have enough info in the question to be able to work out this distance unless I'm missing something?

View attachment 271134

There is enough info. It might be more obvious if you show point C and consider the relationship between the line AC and the line of action of the force.

 

[Bolter]

There is enough info. It might be more obvious if you show point C and consider the relationship between the line AC and the line of action of the force.

I tried including line AC in my diagram but I don't see how it'd help me find any angles or lengths.
I thought I could somehow use Pythagoras theorem to the right angle triangle ABF (in my diagram) where I know AB is sqrt(10) but I still have 2 unknown sides so that won't work

 

[haruspex]

I tried including line AC in my diagram but I don't see how it'd help me find any angles or lengths.
I thought I could somehow use Pythagoras theorem to the right angle triangle ABF (in my diagram) where I know AB is sqrt(10) but I still have 2 unknown sides so that won't work

View attachment 271140

What is the distance from C to BF? This is what @Lnewqban was hinting at in post #3.

 

[Bolter]

What is the distance from C to BF? This is what @Lnewqban was hinting at in post #3.

By that do you mean the perpendicular distance from C to BF which is equivalent to length AF as they are parallel to each other?

EDIT: Ok I got distance from C to BF to be 1.414m and assuming that's equal to AF then AF = 1.414m
hence moment is 1.414m * 50N = 70.7Nm

 

[haruspex]

By that do you mean the perpendicular distance from C to BF which is equivalent to length AF as they are parallel to each other?

EDIT: Ok I got distance from C to BF to be 1.414m and assuming that's equal to AF then AF = 1.414m
hence moment is 1.414m * 50N = 70.7Nm

Right.