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NEET PHYSICSMOTION IN A PLANEMedium

Question

A particle of mass 10 g10 \text{ g} moves along a circle of radius 6.4 cm6.4 \text{ cm} with a constant tangential acceleration. What is the magnitude of this acceleration, if the kinetic energy of the particle becomes equal to 8×104 J8 \times 10^{-4} \text{ J} by the end of the second revolution after the beginning of the motion?

A

0.15 m/s20.15 \text{ m/s}^2

B

0.18 m/s20.18 \text{ m/s}^2

C

0.2 m/s20.2 \text{ m/s}^2

D

0.1 m/s20.1 \text{ m/s}^2

Step-by-Step Solution

  1. Concept: According to the Work-Energy Theorem, the work done by the net force on a particle is equal to the change in its kinetic energy (W=ΔKW = \Delta K) . In non-uniform circular motion, the tangential force FtF_t does work over the distance covered.
  2. Formulas:
  • Tangential Force: Ft=matF_t = m a_t
  • Work Done: W=Fts=matsW = F_t \cdot s = m a_t s
  • Distance covered in nn revolutions: s=n×2πRs = n \times 2\pi R
  1. Given Values:
  • Mass (mm) = 10 g=102 kg10 \text{ g} = 10^{-2} \text{ kg}
  • Radius (RR) = 6.4 cm=6.4×102 m6.4 \text{ cm} = 6.4 \times 10^{-2} \text{ m}
  • Kinetic Energy (KK) = 8×104 J8 \times 10^{-4} \text{ J} (Initial Ki=0K_i = 0)
  • Revolutions (nn) = 2
  1. Calculation:
  • Distance (ss) = 2×2π×(6.4×102)=4π(6.4×102) m2 \times 2\pi \times (6.4 \times 10^{-2}) = 4\pi (6.4 \times 10^{-2}) \text{ m}
  • Applying Work-Energy Theorem: mats=Km a_t s = K (102)at[4π(6.4×102)]=8×104(10^{-2}) a_t [4\pi (6.4 \times 10^{-2})] = 8 \times 10^{-4} at=8×104102×4π×6.4×102a_t = \frac{8 \times 10^{-4}}{10^{-2} \times 4\pi \times 6.4 \times 10^{-2}} at=8×1044π×6.4×104=825.6πa_t = \frac{8 \times 10^{-4}}{4\pi \times 6.4 \times 10^{-4}} = \frac{8}{25.6 \pi} at=13.2π13.2×3.1416110.05a_t = \frac{1}{3.2 \pi} \approx \frac{1}{3.2 \times 3.1416} \approx \frac{1}{10.05} at0.1 m/s2a_t \approx 0.1 \text{ m/s}^2

Exam Context & Concepts Covered

This question aligns with the NEET PHYSICS syllabus, specifically targeting concepts from MOTION IN A PLANE. Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

PHYSICSMOTION IN A PLANEparticlecircleradiusconstanttangential

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