Resultant of Coplanar Concurrent Forces

Applied Mathematics — Second Secondary

Common mistakes

Comparison aspect	Main idea	Keywords
Mistake	adding the magnitudes of the forces directly instead of adding their components. Correct: the resultant is not the sum of the magnitudes unless all the forces act along one line in the same direction	addingmagnitudesforcesdirectly
Mistake	forgetting the negative sign of a component that points in the negative direction as in Example (2) where ΣX = −4 and not 4. Correct: every component pointing in the negative direction of its axis is negative	forgettingnegativesigncomponent
Mistake	writing the angle given by the calculator without checking the quadrant. Correct: if ΣX is negative the angle lies in the second or third quadrant	writinganglegivencalculator
Mistake	forgetting that the resultant is zero when ΣX = ΣY = 0. Correct: this means the body is in equilibrium	forgettingresultantzeroCorrect

Resultant of Coplanar Concurrent Forces · 5 / 6