Question

An athlete in the olympic games covers a distance of 100m in 10s. His kinetic energy can be estimated to be in the range [ AIEEE 2008] ​

Answer 1

Explanation:

Distance = 100 m

Time Taken = 10 seconds

So,

Velocity of man is 10 m/sec

as :-

$velocity = \frac{distance}{time}$

And,

Let mass of athlete be m kg

so,

Kinetic Energy Becomes:-

$k.e = \frac{1}{2}m {v}^{2} \\ \\ = \frac{1}{2}m \times 100 \\ \\ = 50m \: joules$

Now,

Mass of athlete can range between 40 kg to 80 kg (say)

so,

Kinetic Energy could range between :-

2 kiloJoules to 4 kiloJoules

NOTE:- Depends on the range of mass taken.It is possible one can assume mass of athlete in range 50-100 kg or something different.

If in MCQ type question,Range can be taken as per options given.

Answer 2

• Explanation:- The given question vis somewhat based on approximation . Let mass of athelete be 40 kg to 80 kg [∵ v = distance /time = 100/10 = 10 m/s ] ∴ approax velocity from the given data is 10m/s

Assuming mass (m₁)= 40 kg and v = 10m/s

• So , kE₁ = 40× 10² / 2 = 2000j

Assuming Mass(m₂) = 80 kg and v = 10m/s

• Since , kE ₂ = 80 × 10²/2 = 4000j

So it in range of 2000 j to 5000 j .

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