Question

a skateboarder uses a force of 17 n to increase his speed from 4 m/s to 9 m/s in a time interval of 6 s. what is the skateboarders mass?

Explanation:

Step1: Calculate acceleration

Use the formula \(a=\frac{v - u}{t}\), where \(v = 9\ m/s\), \(u = 4\ m/s\), \(t = 6\ s\).
\(a=\frac{9 - 4}{6}=\frac{5}{6}\ m/s^{2}\)

Step2: Calculate mass

Use Newton's second law \(F = ma\), where \(F = 17\ N\), \(a=\frac{5}{6}\ m/s^{2}\). Then \(m=\frac{F}{a}\).
\(m=\frac{17}{\frac{5}{6}}=17\times\frac{6}{5}=\frac{102}{5} = 20.4\ kg\)

Answer:

\(20.4\ kg\)