An athlete in the olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in the range

Option 1)

2,000 \; J - 5,000\; J

Option 2)

200 \, \, J - 500 \, \, J

Option 3)

2\times 10^{5}J-3\times 10^{5}J

Option 4)

20,000 \, \, J - 50,000 \, \, J

Answers (1)

As we discussed in 

Kinetic energy -

k= \frac{1}{2}mv^{2}

- wherein

m\rightarrow mass

v\rightarrow velocity

kinetic Energy is never negative

 

  

Initial velocity = 0 

Final velocity vf.

    S=ut + \frac{1}{2}at^{2}

\Rightarrow\ 100=0 + \frac{1}{2}\times a\times 100

    a = 2 m/s2

Maximum speed = at = 20 m/s2

Maximum K.E.=\frac{1}{2}mv^{2}    (Assume m = 50 kg)

    =\frac{1}{2}\times 50\times 400=10,000J

If it run with constant velocity v = 10 m/s

Then K.E.=\frac{1}{2}\times 50\times 100=2500

So it lies between 2500 to 10,000 J.

Correct option is 1


Option 1)

2,000 \; J - 5,000\; J

This is the correct option.

Option 2)

200 \, \, J - 500 \, \, J

This is an incorrect option.

Option 3)

2\times 10^{5}J-3\times 10^{5}J

This is an incorrect option.

Option 4)

20,000 \, \, J - 50,000 \, \, J

This is an incorrect option.

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