Question

Two forces of 20 N and 10 N are making an angle of 120° with each other. Find a single pull that would (a) replace the given forces system (b) balance the given forces system. ((a)FR = 17.32 N, OR = 30°, (b) FR = 17.32 N, OR = 210°)​

Answer 1

Explanation:

Let, P and Q be the two forces having magnitudes 15 Newtons and 20 Newtons respectively. They are acting at an angle α = 60°.

Let, R be the resultant vector. Vector R acts at an angle θ with vector P.

So, |R^2| = 15^2 + 20^2 + 2 * 15 * 20 * cos 60°

Or, |R^2| = 225 + 400 + 300 = 925

Or, |R| = 30.4138 Newtons

So, tan θ = (20 * sin 60°) / {15 + 20 * cos 60°}

Or, tan θ = (10√3) / (15 + 10) = (10√3) / 25

Or, tan θ = (2√3) / 5 = 0.69282

Or, θ = 34.715°

So, magnitude of the resultant force = 30.4138 Newtons and the resultant force acts at an angle 34.715° with the 15 Newton magnitude force.