Example Problem

Given in the illustration below of a painter (with a mass of 70 kg) standing on the edge of an elevated plaform. Determine the plank support reactions if the plank she is standing on weighs 8kg.

First.... convert to forces!

Wt x 9.81 = newtons

about the force exerted on your head when one apple falls on it. An item which exerts a force of about 0.5 N is the maximum that a "normal" person can lift. This is approximatly equal to a bag of cement. A small car is about 10 N worth of force.

create FBD

sum moments to determine raction at roller

sum vertical forces to determine second reaction

check

Copyright © 1997 by Chris H. Luebkeman