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Q4.4: NCERT Physics - Part 1 LAWS OF MOTION 4.4 Solution: One end of a string of length l is connected to a particle of…
⚠️ Common Exam Traps & Conceptual Pitfalls
Students often treat the required centripetal term $mv^2/l$ as a separate force and subtract or add it to the tension, forgetting that the tension itself is the sole radial force providing the centripetal acceleration. Remember: the net inward force on the particle is just the tension $T$, which already equals $mv^2/l$.
One end of a string of length l is connected to a particle of mass m and the other to a small peg on a smooth horizontal table. If the particle moves in a circle with speed v the net force on the particle (directed towards the centre) is: (i) T, (ii) T - mv_/l, (iii) T + mv_/l, (iv) 0. T is the tension in the string. [Choose the correct alternative].
Step-by-Step Verified Solution
**Answer:** (i) T
**Step-by-Step Explanation:**
The particle moves in a horizontal circle on a smooth table. The only force directed towards the centre is the tension T in the string. This tension provides the centripetal force:
The net force on the particle directed towards the centre is T [citation:1][citation:3][citation:20].
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