91Ó°ÊÓ

It is given that,

$$\begin{gathered} v=9.20\mathrm{m}/\mathrm{s} \\ {\mathrm{a}}_{\mathrm{c}}=3.80\mathrm{m}/{\mathrm{s}}^2 \end{gathered}$$

This problem deals with the centripetal acceleration. Centripetal acceleration is the acceleration of a body traversing a circular path. The sprinter is running on a circular track, so the net force will be the centripetal force. The radius and period of sprinter using the equation of centripetal acceleration and period in circular motion can be found.

Formulae:

The centripetal acceleration is given by,

$$\begin{gathered} a_c=\frac{v^2}{r} \\ v=\frac{2\mathrm{Ï€}r}{T} \end{gathered}$$ (i)

(ii)

Where, r is radius, v is velocity, Tis time and a is an acceleration.

Using equation (i),

$$\begin{gathered} r=\frac{v^2}{a_c} \\ =\frac{{\left(9.20\right)}^2}{\left(3.80\right)} \\ =22.27\mathrm{m}\mathrm{or}22.3\mathrm{m} \end{gathered}$$

Using equation (ii),

Time will be,

$$\begin{gathered} T=\frac{2\mathrm{π}r}{v} \\ =\frac{\left(2×3.14×22.27\right)}{\left(9.20\right)} \\ =15.20\mathrm{s} \end{gathered}$$