The time taken for the athlete to finish the race is 20 s (Option A)
<h3>What is power? </h3>
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
<h3>How to determine the time </h3>
- 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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Answer and explanation:
When you are changing a car tire, the most important thing is to keep the total diameter as equal as possible.
The total car tire diameter can be calculated as:

The profile of this tire is 75 (the higher/taller relation), therefore a 5 percent lower profile would be:
pr=0.95·75=71.25
The problem is that the profiles are normalized and the nearest profile available is 70.
If we take a theorical tire with a profile of 71.25:

The theorical tire size should be 205/71 R15.
If we look for a real tire size, we should look for a tire with a diameter nearest to 26.5'' and a profile of 70.
The best option for real tire size is: Tire 225/70 R14 (wheel diameter of 26.4'') or 205/70 R15 (wheel diameter of 26.3'').
Answer:
40 N
Explanation:
F=ma where F is the applied force, m is the mass of object and a is the acceleration.
Since there is no friction, substituting 20 Kg for m and 2 m/s squared for a then we obtain
F=20*2=40 N