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Question:

A force of 40 N acts on a point B at the end of an L-shaped object, as shown in the figure. The angle θ that will produce maximum moment of the force about point A is given by:

tanθ=12

tanθ=4

tanθ=14

tanθ=2

Solution:

Moment of force about point A will be given as τ = Fcosθ × 4 + Fsinθ × 2
For maximum τ, dτ/dθ = 0
0 = -4Fsinθ + 2Fcosθ
tanθ = 12