Question

8(b). Two forces 30 N and 40 N act at right angles to each other. Determine, by scale drawing, the magnitude and direction of the resultant force, using a scale of 1 cm to 5 N.

Accepted Answer

By Pythagoras' theorem, resultant R = √(30²+40²) = √2500 = 50 N. Using tanα = opposite/adjacent = 30/40 = 0.75, α = tan⁻¹(0.75) ≈ 36.9° from the 40 N force. On the scale drawing (1 cm = 5 N), the resultant line R would measure 10 cm, drawn at about 37° to the 40 N force (i.e. about 53° from the vertical).

WAEC Physics 2015 Theory — Question 9

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