A uniform board of mass 12 kg is held up by two posts, as shown in the diagram.
ID: 2124974 • Letter: A
Question
A uniform board of mass 12 kg is held up by two posts, as shown in the
diagram. Find the upward force that each post exerts on the board. You MUST begin
with a free-body diagram, showing the upward and downward forces. There are no
horizontal forces. As always, we assume that the force of gravity acts at the center of
mass. (Partial answer: the left-hand post exerts 29.4 N up.)
The left post is 2 ft in from the left and the right post is 4 feet in from the right. The board is 10 feet long.
The illustration won't allow me to copy and paste so I apologize.
Any help would be greatly appreciated!
Explanation / Answer
net torque should be zero
TL*3 - TR*1 = 0
TL = TR/3
and TL + TR = 12*9.8 = 117.6
TR/3 + TR = 117.6
TR = (3/4) * 117.6 = 88.2 N
TL = 117.6 - 88.2 = 29.4 N
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.