Q62 / 90 · JEE Main 2022 (28 Jul Shift 2) · Physics

At time t=0 a particle starts travelling from a height 7z^ cm in a plane keeping z coordinate constant. At any instant of time, it's position along the x and y directions are defined as 3t and 5t3 respectively. At t=1 s acceleration of the particle will be

  • A
    -30y
  • Correct answer
    B
    30y
  • C
    3x+15y
  • D
    3x+15y+7z^

Solution

The position vector of the particle can be written as,

r→=3ti^+5t3j^+7k^

The velocity of the particle will be, 

v→=dr→dt=3i^+15t2j^

Now the acceleration of the particle will be,

a→=dv→dt=d2r→dt2=30tj^

At t=1 s⇒d2rdt2=30j^

Hence, the correct answer is option: 'B'.

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