00:01
In this question we have given a trust member and we have to find forces in all the member of this trust.
00:08
First of all i find the reaction force at point b and c.
00:13
Let this is rv and this is rc in upper direction.
00:20
Here we have two unknowns and by using two equilibrium equation we can find the value of rb and rc.
00:26
First equilibrium equation is net force in wide direction is 0 so that is rb plus rc is equals to 20 newton and one is moment balance that is moment about point b is equal to 0 so this is minus p into 3 minus rc into 3 is equals or i can say plus 10 into 6 is equals to 0 so from here we get r c that is 10 newton this is our equation first and from equation first we get rb that is 10 newton so this is our reaction now we have to find forces in all that member so first i am using for this joint method in this joint method we have to balance the forces on each joint so first i am taking the joint that is joint a.
01:52
So first of all i am going to show the forces on joint a that is 10 newton which is acting in vertical direction.
02:02
One is let the force due to the member ab which is fab and one force is due to the member that is af which is faf.
02:16
Now i am going to balance the forces in action.
02:20
Direction so first i'm going to balance in y direction that is force in y direction is equal to 0 so this is this angle is 45 degree so f a .f sign 45 is equal to 10 newton from here we get the value of f a .f that is 10 root 2 and this will come into tension this is the force in member a .f now using force balance in x direction that is net force in x direction is equal to 0.
03:06
So from here we get fab is equal to f af cost 45 degree.
03:13
So this is 10 root 2 and this is 1 by root 2.
03:17
From here we get force in ab member that is 10 newton and this will come into compression.
03:35
This is the joint a.
03:37
Now i am going to take that is joint.
03:45
First of all i am going to show the forces on joint d that is one force which is given to us that is p is equal to 10 newton another force is due to the member cd let this is acting in this direction which is f cd and one force is due to the member that is f cd and one force is due to the member that is f e d.
04:11
This angle is 45 degree now i am going to balance the forces in x and y direction net force in y direction is equal to 0 from here we get f e d sine 45 is equal to 10 newton from here we get f ed that is 10 root 2 and this is into tension this is the force in ed member now balance the force into x direction so net force in x direction is equal to 0 from here we get f cd is equal to f e d cost 45 degree so from here we get 10 root 2 into 1 by root 2 which that is f cd is equals to 10 newton and this is in compression so this is the force in cd member this is for section joint d now i am going for joint b or i can first calculate for joint c.
05:46
So this is our joint c.
05:49
And i'm going to show the forces that acts on this joint...