Tension in Strings, Ropes, Rods, and Chains
An ideal string over an ideal pulley has uniform T; a cut through a massive connector exposes the local carried force.
Why this shows up in the exam
Massive ropes · Accelerating rods · Pulley clamp loads
Learn the idea
Cut the connector; tension is set by the mass supported or accelerated beyond the cut. A massless ideal string has one tension, while massive ropes generally do not.
🧠 Memory hook: Tension pulls away from a cut.
Get this one clearly and it pays off every single time it shows up in the paper. 🎯
Formulas & facts to keep ready
- T₁ = T₂ = T — same ideal string
- T = m_supported(g+a) — vertical accelerating support
- T = F m_remaining/m_total — uniform rope pulled on a smooth floor
How to approach it
- 1Cut at the point
- 2Choose one side
- 3Apply Newton’s law
Common slip-ups that cost marks
- •Uniform tension in massive rope
- •Tension pushing
- •Ignoring pulley weight
🌟 That's the whole idea — you've got this. Try the practice set below; every question you attempt makes it stick a little harder.
Original chapter practice
Original questions for this chapter, not past-paper questions or an exact mapping to this individual concept.
A 2 kg block moves on a horizontal rough surface with coefficient of kinetic friction 0.2. A horizontal force of 10 N acts on it. Take g = 10 m/s^2. What is its acceleration?
More from Laws of Motion
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Analyze the forces involved in uniform and non-uniform circular motion, including centripetal force, tension, and friction.
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Inertia and Inertial Frames
In an inertial frame, sum F_ext = 0 implies a = 0. Earth-fixed frames are approximate when rotational effects are negligible.
Newton’s Second Law in Vector Form
In an inertial frame sum F_ext = dp/dt; for constant mass this becomes m dv/dt = ma.