8.4. Applications of Equilibrium Conditions http://www.ck12.org
Answer: Even though only one equation of equilibrium∑τ=0 was explicitly used to solve the problem, both
conditions must still be satisfied. Therefore:
∑
y
F=Fnet y= 0 →FN− 264. 9 − 81. 4 − 323. 7 = 0FN= 670 N
Illustrative Example 2: The Daredevil
A daredevil with massmdof 60.0-kg walks along a uniform steel beam with massmbof 270.0-kg, and unknown
lengthL. One-third of the length of the beam hangs over the edge of a tall building. How far can the daredevil walk
along the beam without the beam tipping over the edge of the building? Express the answer in terms of the lengthL
of the beam. SeeFigure8.11.
FIGURE 8.11
Answer:We begin by drawing a Free Body Diagram of the steel beam.