00:01
Okay, so in this exercise we have two forces acting on an object at rest.
00:05
This will be our object at rest.
00:08
And they ask to us that we must add a third force, namely f3, such that the object remain at rest.
00:16
Okay? so in order to do this exercise, we must remember newton's second law of motion, which says to us that the sum of all forces acting on an object is going to be equal to the mass of the object times its acceleration.
00:36
So in the first situation, okay, we have two forces acting on an object.
00:41
And if these two forces not cancel, then we are going to have that this object will accelerate.
00:50
But now we want to add a third force in order that we have that the sum f1, plus f2 plus f3 must be equal to zero.
01:08
Okay, this is what we want.
01:11
So in this case, we can see that analytically, f3 must be equal to minus f1 minus f2.
01:25
Okay? so, but f1 f1 is equal to minus f1x, which is going to be the component in i.
01:45
And f2 is equal to f2 in y, f2 in j.
01:54
In j...