A body of mass ( 5 ± 0 . 5 )   kg is moving with a velocity of ( 20 ± 0 . 4 )   m  …

A body of mass (5±0.5) kg is moving with a velocity of (20±0.4) m s-1. Its kinetic energy will be

  1. (1000±0.14) J
  2. (500±0.14) J
  3. (500±140) J
  4. (1000±140) J

Solution

The kinetic energy is given by,

K=12mv2

Differentiating the above equation,

dK=12(v2dm+2mvdv)

Dividing by K,

⇒dKK=dmm+2dvv

⇒dK1000=0.55+2×0.420

⇒dK=100+40=140

⇒KE=(1000±140)J

Asked in: JEE Main 2023 (13 Apr Shift 1)

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