00:01
Let's take a look at this problem where we're asked to figure out the tension force in each of these chain slings be.
00:08
Up here, i'm given a length of the chain that's 5 .9 meters.
00:14
I'm given a max gross weight.
00:16
I'm taking that to be the maximum amount that could be lifted by this crane.
00:23
If we subtract the tear weight from that, we get a payload weight of 28 ,310.
00:30
That tells me that this crate that's actually being lifted has a mass of 28 ,310 kilograms.
00:39
Now, this is actually mass to find weight.
00:43
I need to multiply that by gravity by 9 .8.
00:47
Because the question asks us to give our final answer to an appropriate number of significant figures, and this is my starting number, which has four significant figures, i went ahead and used 9 .801.
01:02
Sorry, i used 9 .807 meters per second squared.
01:06
So this number for g times this mass gave me this is actually the net force on all the chains.
01:17
Well, i have four chains, and it's the net gravity downward force.
01:22
So it's this downward vector here.
01:25
But because i have it on four chains, go ahead and take this number divided by four.
01:30
That's going to give us the force on each of the four chains.
01:34
Dividing this number by four gives me this number.
01:38
You notice i'm keeping more than four significant figures in my calculations, and then we'll round at the end.
01:44
So that's this downward force.
01:46
I'm going to pull this vector over here.
01:49
There's actually four of these vectors, one downward force for each chain...