Physics · Class 11

Strike a hinged rod

During a brief collision the hinge can exert an impulse, so linear momentum of particle plus rod need not be conserved. Its moment about the hinge is zero, allowing angular momentum about that point to determine the final rotation.

Open the interactive experiment →

Strike a hinged rod

கீல் உந்தம் நேர்கோட்டு உந்தத்தை மாற்றலாம்; ஆனால் கீலைப் பற்றிய திருப்புவிசை பூஜ்யம் என்பதால் கோண உந்தம் காக்கப்படும்.

Key notes, relationships and model limits

Key relationship

mvb = (Ml²/3+mb²)ω; Kafter = ½Iω².

Remember

Common trap

A hinge can supply external linear impulse even when angular momentum about the hinge is conserved.

Model limits

Particle hits perpendicular to the rod and sticks at distance b. Hinge impulse has zero moment about the hinge, so angular momentum there is conserved during impact. Gravity is ignored after impact.

What you will learn

Choose an appropriate conservation law for a constrained impact.

Try the experiment

Try both scenarios, change one control, and predict the result before checking the graph and readouts.

Think of it this way

Change one input while keeping the others fixed, as you would in a controlled experiment.

Worked example

m=0.5 kg, v=4 m/s, b=1 m gives L=2 kg·m²/s. For M=2 kg and l=2 m, I=2×4/3+0.5=3.167 kg·m² and ω=0.632 rad/s.

Why this matters

The model connects strike a hinged rod with an observable reading. Check the equation and assumptions before applying it.

Before you start

SI units · algebra · graph reading

Check your understanding

Which quantity is conserved during this sticking impact?

Total linear momentum of particle plus rod
Angular momentum about the hinge
Total kinetic energy

Read the explanation

The hinge impulse has no lever arm about the hinge; the impact is inelastic and loses kinetic energy.

Course connection: Class XI Chapter 6. Consult the roadmap for CBSE, NEET, JEE Main and Advanced scope.