Physics Help Forum Static Force Analysis

 Kinematics and Dynamics Kinematics and Dynamics Physics Help Forum

 Mar 16th 2017, 08:15 AM #2 Physics Team     Join Date: Jun 2010 Location: Naperville, IL USA Posts: 2,179 To get you started I suggest consider the torque about the pin joint connecting the boom to the bucket, which I labeled point A in the attached figure. Because this is a pin joint, the sum of torques acting on the bucket about point A must be zero. I have attached a free body diagram for the bucket - the torques that need to be considered are due to (1) the weight of the bucket - 'W', (2) the horizontal force of the bucket link, and (3) the vertical force of the bucket link. Note that because of the pin connection between the bucket link and the bucket at point B there is no torque present at that joint either. So, sum of torques about point A yields: $\displaystyle \Sigma T = (W \times D1) - (F_{BL_X} \times D2) - (F_{BL_Y} \times D3) = 0$ You also know that the ratio of F_BLY to F_BLX must equal the tangent of angle theta (again, because the pin joints at either end of the bucket link cannot transmit any torque): $\displaystyle F_{BL_Y} = F_{BL_X} \tan \theta$ Now you have two equations in two unknowns (F_BLX and F_BLY), so you can solve for these. I suggest you do this calculation, then see if you can next work out the horizontal and vertical forces at point A. Please post back with what you find. Attached Thumbnails   Last edited by ChipB; Mar 16th 2017 at 08:18 AM.