Mechanics - How It Appears in JEE

6 recurring patterns. Learn the pattern, recognize it in 5 seconds, apply the right approach.

FBD and Force Resolution

Pattern

Find acceleration, tension, or normal force in a system of blocks/pulleys

How to recognize

Question involves blocks on surfaces, inclines, or connected by strings/pulleys

→ Draw FBD for each body. Resolve forces along and perpendicular to motion. Write Newton's second law for each body. Solve simultaneous equations.

Friction Problems

Pattern

Determine if body moves, find friction force, or find minimum force to move

How to recognize

Question mentions rough surface, coefficient of friction, or asks about sliding/toppling

→ First check if applied force exceeds maximum static friction. If yes, use kinetic friction. If no, friction = applied force. For toppling, check torque condition.

Work-Energy Theorem Application

Pattern

Find speed, distance, or work done using energy methods

How to recognize

Question asks for final speed after displacement, or work done by a force over a path

→ Identify all forces. Calculate work done by each (W = Fd cos theta or integral). Apply W_net = delta KE. For conservative systems, use energy conservation.

Circular Motion Problems

Pattern

Find tension, speed, or radius in circular motion

How to recognize

Body moves in circle (horizontal, vertical, conical pendulum, banked road)

→ Identify centripetal direction. Apply Newton's second law radially: net radial force = mv^2/r. For vertical circles, consider position-dependent speed and tension.

Collision and Momentum

Pattern

Find velocities after collision, energy loss, or impulse

How to recognize

Two bodies collide or explode. Question mentions elastic/inelastic/perfectly inelastic

→ Apply momentum conservation. Use e (coefficient of restitution) for velocity relation. For perfectly inelastic, bodies stick. Check if energy is conserved (only for elastic).

Power and Variable Force

Pattern

Find instantaneous power, or motion under variable force/power

How to recognize

Question mentions power, F(x), or force as function of position/velocity

→ P = F.v for instantaneous power. For variable force, integrate F dx for work. For constant power, use P = Fv = ma.v and integrate to find v(t) or x(t).

Electrostatics & Capacitors

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