Question

A 55 kg track and field athlete has an average power output of 5.4 kW during the 200 meter dash. How quickly did she finish the race?
Group of answer choices

a. 20 s

b. 22 s

c. 23 s

d. 18 s

Answer 1

The time taken for the athlete to finish the race is 20 s (Option A)

What is power?

Power is simply defined as the rate at which work is done. It can be expressed mathematically as

Power (P) = work (W) / time (t)

But

Work = weight × distance

Therefore,

Power = (weight × distance ) / time

How to determine the time

• Mass (m) = 55 Kg
• Acceleration due to gravity (g) = 9.8 m/s²
• Weight = mg = 55 × 9.8 = 539 N
• Power (P) = 5.4 KW = 5.4 × 1000 = 5400 W
• Distance (d) = 200 m
• Time (t) =?

Power = (weight × distance ) / time

5400 = (539 × 200) / t

5400 = 107800 / t

Cross multiply

5400 × t = 107800

Divide both side by 5400

t = 107800 / 5400

t = 20 s

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