00:01
Okay, so we've got this situation here and we want to start by drawing a free body diagram of all the forces present.
00:06
So we've got our beam and in the center of the beam its weight is going to act downwards.
00:14
So i'll call this w beam.
00:18
We've then also got the buoy and the weight of the buoy will also act downwards.
00:27
Then 0 .4 meters away from the buoy we have the reaction of the right hand support.
00:35
That's going to act upwards on the beam.
00:39
That's the weight of the beam pressing down on the support.
00:41
Newton's third law generates an equal and opposite force in response to that.
00:47
R2 and we've got the reaction force from the left hand support right the way over here which we'll call r1 and this is 2 .5 meters away from the center of the beam obviously and 3 meters away from the other support.
01:07
So that should be everything we need.
01:10
We then go on to part b which asks us to use the equilibrium of torque or of moments to find the reaction force at the left support which i've called r1 here.
01:26
So what we're doing is we're going to take the pivot to be our second.
01:31
So i shouldn't really put it there.
01:33
We'll take the pivot to be here at our second reaction.
01:40
So that's where we're measuring from.
01:43
So the forces so that's here.
01:47
The forces that are going clockwise then are r1 that's going clockwise and the weight of the buoy that's going clockwise as well...