Q129 / 160 · TS EAMCET 2021 (05 Aug Shift 1) · Physics

A constant force of 5 N accelerates a stationary particle of mass 500 gm through a displacement of 5m.The average power delivered is

  • A
    6.25 W
  • Correct answer
    B
    25 W
  • C
    62.5 W
  • D
    50 W

Solution

Given, force, F=5 N

Mass, m=500 g=5×10-1 kg

Displacement, s=5 m

Work done is given by W=F→·s→=Fscosθ

Let's assume the angle between force and displacement to be zero. Then work will be,

W=Fs=5×5=25 J

Let the time taken to travel the displacement of 5 m be t s.
Applying Newton's second law of motion,

F=ma

⇒a=55×10-1⇒a=10 m s-2

From the third equation of motion,

s=ut+12at2

⇒5=0+12×10t2,           initial velocity, u=0

⇒t=1 s

The average power is given by

Pavg=Total worktotal time taken=251=25 W

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

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