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GATE 2020 CE (CE1) – Question 39

Engineering Mechanics · System of forces, free-body diagrams, equilibrium equations · 2 marks · Multiple choice

The shown rigid weightless platform PQRS slides freely vertically, held by weightless member OJ and four weightless frictionless rollers. O and J are pins. A 90 kN block rests as shown. Find horizontal reaction component magnitude at pin O (kN).

Diagram for GATE 2020 CE (CE1) question 39
  1. 90
  2. 120
  3. 150
  4. 180

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Show answer and explanation

Correct answer: (B) 120

Explanation

Guide rollers exert horizontal forces only, so OJ supplies the entire 90 kN vertical support. As a two-force member its component ratio follows the 4:3 geometry. Horizontal reaction magnitude is $90(4/3)=120$ kN. **B**.