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Motion In A Plane

Question
CBSEENPH11020472

A body of mass m accelerates uniformly from rest to v1 in time t1. The instantaneous power delivered to the body as a function of time t is

  • fraction numerator mv subscript 1 straight t over denominator straight t subscript 1 end fraction
  • fraction numerator mv subscript 1 superscript 2 space straight t over denominator straight t subscript 1 superscript 2 end fraction
  • fraction numerator mv subscript 1 straight t squared over denominator straight t subscript 1 end fraction
  • fraction numerator mv subscript 1 superscript 2 straight t over denominator straight t subscript 1 end fraction

Solution

B.

fraction numerator mv subscript 1 superscript 2 space straight t over denominator straight t subscript 1 superscript 2 end fraction

Let the constant acceleration of body of mass m is a.
From equation of motion
v1 = 0 + at1
⇒ a = t2/t= ...... (i)
At an instant t, the velocity v of the body v = 0 + at
straight v space equals space straight v subscript 1 over straight t subscript 1 straight t space space.... space left parenthesis ii right parenthesis
therefore space instantaneous space power
straight p space equals Fv
space equals mav space space left parenthesis because space straight F space equals space ma right parenthesis
equals space straight m open parentheses straight v subscript 1 over straight t subscript 1 close parentheses space straight x open parentheses straight v subscript 1 over straight t subscript 1 space straight x space straight t close parentheses space left square bracket space From space equ space left parenthesis straight i right parenthesis space and space left parenthesis ii right parenthesis
space equals space fraction numerator mv subscript 1 superscript 2 straight t over denominator straight t subscript 1 superscript 2 end fraction