Still having problems with statics.

[jespergreen]

Hi all.

I have a construction with the force affecting it from 4 sides.
The 4 forces are:
F1 = 430N
F2 = 490N
F3 = 385N
F4 = 430N

When i try to calculate the force, i dont get the correct result according to the book. (1189N)

The way i have learned it from the book is like this:

430*sin 330
490*sin 60
385*sin 0
430*sin 90



What am i doing wrong?

 

[tkhunny]

You are using your calculator incorrectly. You have degrees and it is expecting radians.

You should have had a clue something is VERY wrong when your cosine total was negative. Look at your drawing. No way that could happen.

 

[jespergreen]

aah, ok.
I can see the result on my old old calculator are different (correct).
I wonder how i change to radians in the online calculator? https://www.symbolab.com/

The negativ answer did not alert me, since the previous example in the book got a negative answer too :/


Thank you for your time and patience

PS. i think i will need a better/newer calculator....Cant figure the online one out, even when i did how you told me the answer differs

 

[mmm4444bot]

I wonder how i change to radians in the online calculator? https://www.symbolab.com/

To the left of the button labeled Degrees, there is a button labeled Radians.

Click it. :cool:

 

[jespergreen]

Yeah, thx....But the answer is still wrong
I will try another calculator.

 

[jespergreen]

Microsoft Mathematics seems to do the trick.

 

[tkhunny]

Unit conversion: \(\displaystyle degrees\cdot\dfrac{\pi}{180\;degrees} = radians\)

Technically, "Radians" isn't really a unit. It's just numbers.