WJEC Maths for A2 − Pure & Applied Practice Tests

6 Types of force, resolving forces and forces in equilibrium 77 ➍ A lamp is hung from a point P and it is supported by two light rods PQ and PR. Rod PQ is horizontal and rod PR is inclined at an angle θ to the horizontal, where sin  θ = 0.5. The mass of the lamp is 2 kg. Ʌ R P Q (a) Explain the difference between a thrust and a tension in a light rod. [2] (b) Redraw the diagram marking all the forces acting. [2] (c) Calculate the thrust in rod PR. [3] (d) Calculate the tension in rod PQ. [3] (e) Explain why the modelling assumption that the rods are light was made in this question. [1]