00:01
Hi, in this question we have to hold your arm straight out with the album muscle, which is fm in the diagram, pulls the angle of 13 degrees.
00:12
So we're given the mass of the arm has 4 .2 kilograms.
00:16
Once calculate the force fm.
00:17
So i'm going to use the torque and the total clockwise torque must be called the total counterclockwise torque.
00:23
So the fm produces a counterclockwise torque and the mass, the weight produces a clockwise torque.
00:28
So the torque is a product of the force and the distance from the private rotation.
00:36
So we have fm and all we need is for the force to be perpendicular to the arm.
00:43
So we need to find the component of fm in the vertical direction.
00:47
So this is going to be fm sine theta.
00:52
So fm sine theta times the distance to the pivot, which is at this point 12 centimeters, is equal.
01:00
To the weight mg which is already perpendicular so we don't need to result that times 24 which is the distance to the private so from here we can solve for fm so fm we call to mass is so let's write the equation first mg time is 24 divided by 12 sine theta which is going to give us um 4 .2 times 9 .81 times 24 divided by 12 sine beta which the angle is 13 degrees so this will give us 366 newtons approximately next want to find so this for part a for part b want to find the force the mountain direction of fj which is a force exerted by the shoulder joints on the upper arm.
02:11
So what we need is to find the resultant of these two forces, which is the width going downwards, and then we have the vertical component of these and we have the horizontal components of this.
02:24
So for our total force in the vertical direction, we have submission fy is going to be called to fm sign theta minus mg because these two are in opposite directions.
02:42
And this mg...