Resolution of Forces

Applied Mathematics — Second Secondary

Common mistakes

Comparison aspect	Main idea	Keywords
Mistake	using sin instead of cos for the horizontal component. Correct: when the angle is measured from the horizontal axis the horizontal component is F cos θ and the vertical component is F sin θ	usinginsteadhorizontalcomponent
Mistake	leaving the calculator in radian mode. Correct: always check that the calculator is in degree mode before calculating	leavingcalculatorradianmode
Mistake	adding the two components instead of squaring them when finding the magnitude. Correct: F = √(F_x² + F_y²); the components are never added directly.	addingcomponentsinsteadsquaring
Mistake	ignoring the sign of a component when deciding the quadrant. Correct: draw the axes and decide quadrant the force lies in before writing the final angle	ignoringsigncomponentdeciding

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