Engineering Mechanics (Mech)

SCOPE for RRB JE Mechanical:

Statics:

• Forces, moments, equilibrium of rigid bodies.
• Resultant force, polygon law, varignon's theorem.
• Lami's theorem: F1/sin α = F2/sin β = F3/sin γ.
• Free body diagrams.

Dynamics:

• Kinematics: motion equations v = u + at, s = ut + ½at², v² = u² + 2as.
• Newton's laws of motion.
• Work-Energy theorem.
• Momentum and impulse.

Friction:

• Static friction: f_s ≤ μ_s · N.
• Kinetic friction: f_k = μ_k · N.
• Angle of repose: tan θ = μ.
• Inclined plane problems.

Common JE Mechanical exam topics:

• Center of gravity & centroid of areas.
• Moment of inertia (I = bh³/12 for rectangle).
• Truss analysis (method of joints, method of sections).
• Belt friction, screw jack.
• Simple machines (lever, pulley, wheel & axle, inclined plane, wedge, screw).

Key formulas:

• Work = F × d × cos θ.
• KE = ½ mv²; PE = mgh.
• Power = F × v.

RRB JE focus: numerical problems with unit conversion, basic formula application.