Question

Two forces whose magnitudes are in ratio of 3:5 give a resultant of 35N. If the angle of inclination is 60°, calculate the magnitude of each force.

(a) 15N and35N

(b) 15N and 25N

(c) 10N and 15N

(d) 20N and 5N

Answer 1

Right choice is (b) 15N and 25N

Explanation: P = 3x and Q = 5x R = 35N θ = 120°

R = (sqrt{P^2 + R^2 + 2PQcosθ})

35 = 7x or x = 35/7 = 5

P = 15N Q = 25N.