Free body diagram
Example: Construct a free body diagram of the ladder.
Strategy: Identify all external forces acting on the ladder by isolating the ladder from gravity,
from the vertical wall, and from the floor.
Show the coordinate system, the geometry, the dimensions, the angle, and all “external”
forces acting on the ladder (by the surroundings). The figure below shows the FBD of the ladder.
The table below lists the external forces acting on the ladder.
Na is the normal force exerted by the vertical wall on the ladder
Nb is the normal force exerted by the floor on the ladder
Fb is the friction force exerted by the floor on the ladder
W is the weight caused by gravity acting on the ladder
Note: The rectangular coordinate system is x-y with the origin at the lower end of the ladder.
The ladder makes an angle of θ with respect to the floor.
The ladder has length, L, with the weight concentrated at the middle of the ladder.
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Copyright © 2019 Richard C. Coddington All rights reserved.
