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A body of mass 1 kg is thrown upwards with a velocity 20 m/s. It momentarily comes to rest after attaining a height of 18 m. How much energy is lost due to air friction? (g=10\: m/s^{2})

  • Option 1)

    30 J

  • Option 2)

    40 J

  • Option 3)

    10 J

  • Option 4)

    20 J

 

Answers (1)

best_answer

As discussed in

Net work done by all the forces give the change in kinetic energy -

W=frac{1}{2}mv^{2}-frac{1}{2}mv{_{0}}^{2}

W= k_{f}-k_{i}

- wherein

m=mass : of: the: body

v_{0}= initial: velocity

v= final: velocity

 

 

 Loss in Energy = \frac{1}{2}mv^{2}-mgh

= \frac{1}{2} \times 1\times 400-1\times 18\times 10

= 200-180 = 20J


Option 1)

30 J

This solution is incorrect

Option 2)

40 J

This solution is incorrect

Option 3)

10 J

This solution is incorrect

Option 4)

20 J

This solution is correct

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perimeter

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