Question

1. in the 1988 seoul olympics, ben johnson infamously ran 100 m in 9.79 seconds. determine his average speed in kilometers per hour, correct to the nearest tenth.

Explanation:

Step1: Convert meters to kilometers

Since \(1\) kilometer \( = 1000\) meters, \(100\) meters \(=\frac{100}{1000}=0.1\) kilometers.

Step2: Convert seconds to hours

Since \(1\) hour \( = 3600\) seconds, \(9.79\) seconds \(=\frac{9.79}{3600}\) hours.

Step3: Calculate average speed

The formula for average speed \(v=\frac{d}{t}\), where \(d\) is distance and \(t\) is time. Substituting \(d = 0.1\) km and \(t=\frac{9.79}{3600}\) h, we get \(v=\frac{0.1}{\frac{9.79}{3600}}\).
Using the rule \(\frac{a}{\frac{b}{c}}=\frac{a\times c}{b}\), we have \(v=\frac{0.1\times3600}{9.79}=\frac{360}{9.79}\approx36.8\) km/h.

Answer:

\(36.8\) km/h