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Question: Answered & Verified by Expert
A particle moves such that its position vector rt=cosωti^+sinωtj^ where ω is a constant and t is time. Then which of the following statements is true for the velocity vt and acceleration at of the particle:
PhysicsMotion In Two DimensionsJEE MainJEE Main 2020 (08 Jan Shift 2)
Options:
  • A v is perpendicular to r and a is directed away from the origin
  • B v and a both are perpendicular to r
  • C v and a both are parallel to r
  • D v is perpendicular to r and a is directed towards the origin
Solution:
1400 Upvotes Verified Answer
The correct answer is: v is perpendicular to r and a is directed towards the origin
r=cosωti^+sinωtj^
v=drdt=ω-sinωti^+cosωtj^
a=dvdt=-ω2cosωti^+sinωtj^
a=-ω2ra is antiparallel to r
v.r=ω-sinωtcosωt+cosωtsinωt=0
So vr

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