Theory question 107
StaticsA body of mass 18 kg is suspended by an inextensible string from a rigid support and is pulled by a horizontal force F until the angle of inclination of the string to the vertical is 35°. If the system is in equilibrium, calculate the: (a) value of F; (b) tension in the string. [Take g = 10ms−2]
Show the model answer
Model answer
Resolve: vertically T cos 35° = 180; horizontally T sin 35° = F.
(a) F = 180 tan 35° ≈ 126.0 N.
(b) T = 180/cos 35° ≈ 219.7 N.
Explanation
Resolve the tension into vertical and horizontal parts.