What is the y-component of Fa in statics?

[talmid100]

Hello

I need to find L1 length
but I don't know how to start

 

[timetraveller123]

welcome to physics forum

you mentioned in the question it is statics what are the quantities that have to sum to zero for statics

 

[talmid100]

The question says the system in the picture is in balance find L1 length .

That's it no more info in the question

 

[timetraveller123]

no i was asking you

 

[talmid100]

welcome to physics forum

you mentioned in the question it is statics what are the quantities that have to sum to zero for statics[/QUOTE

The question says the system in the picture is in balance find L1 length .

That's it no more info in the question

 

[timetraveller123]

okay if something is balanced what needs to cancel out

 

[talmid100]

Don't know

 

[timetraveller123]

okay do you know about moments

 

[talmid100]

I know that the formula says m=f*l

but how to proceed I'm not sure

Maybe. - fa*l + f2 *sin 65*3l

 

[timetraveller123]

ok what is fa and what is f2 and why is there 3l

 

[talmid100]

fa is force on point a (which I don't know)
F2 is 35 *sin 65 and 3l should be the distanceI'm totally lost here.

 

[timetraveller123]

your method is correct but i think instead of 3l it should be 3 +L where l is what the question is asking

while this method is valid you don't know what fa is which you need to calculate separetely

what if you take moments about the point a

 

[talmid100]

F2 (35 *(sin 65) * 3 (distance from point a to f2)
equal to 95.16 divide by f1 (20)

95.16/20 = 4.76 so L1 is 4.76 m

 

[timetraveller123]

i think it is correct

do you know how to figure out fa and you might want to check your answer using that method

 

[talmid100]

No I don't know how to figure fa

 

[Delta2]

No I don't know how to figure fa

Use that the sum of all forces must equal zero in a static equilibrium.

 

[talmid100]

I'm not sure if it's correct

Fx=0

Fa= F2(35)*cos (65) = 14.8

 

[Delta2]

You calculated correctly (within a sign +- perhaps) the x-component of Fa. Now calculate the y-component of Fa.