Physics - NLM Question with Solution | TestHub

Each rope segment attached to the leg carries tension equal to the weight of the hanging 3 kg block:

$$T=mg=3\times 9.8=29.4N$$

The leg is stretched by the resultant of two such tension forces with an angle of 30° between them:

$$F=\sqrt{T^2+T^2+2T^2\cos 30^{\circ }}$$

$$F=T\sqrt{2+2\cos 30^{\circ }}=2T\cos 15^{\circ }$$

$$F=2\times 29.4\times 0.966\approx 56.8N\approx 56N$$

Hence the stretching force in the patient's leg is about 56 N.

Therefore option (3) is correct.