GATE 2016 ME (ME1) – Question 41

Engineering Mechanics · Plane trusses and frames · 2 marks · Multiple choice

A two-member truss PQR is supporting a load W. The axial forces in members PQ and QR are respectively

Diagram for GATE 2016 ME (ME1) question 41

$2W$ tensile and $\sqrt3W$ compressive
$\sqrt3W$ tensile and $2W$ compressive
$\sqrt3W$ compressive and $2W$ tensile
$2W$ compressive and $\sqrt3W$ tensile

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (B) $\sqrt3W$ tensile and $2W$ compressive

Explanation

At joint Q, the diagonal must push upward to balance W, so QR is in compression. Its vertical component is FQR sin30°=W, giving FQR=2W. Horizontal equilibrium gives FPQ=2Wcos30°=sqrt3W in tension. Therefore **sqrt3W tensile and2W compressive, B**.