Question

An athlete completes one round of a circular track of diameter $200m$ in $40s$. What will be the distance covered and the displacement at the end of $2$ minutes $20s$?

Answer 1

$\text{Total time}=2min20s$

$\Rightarrow \text{Total time}=140s$

Time to complete one round-

$t=40s$

Total number of rounds-

$n=\frac{T}{t}$

$\Rightarrow n=\frac{140}{40}$

$\Rightarrow n=3.5\text{round}$

Now distance$\left(d\right)$-

Distance in one round $=\pi D$

$D=200m$; diameter

$d=3.5\times \pi \times 200$

$\Rightarrow d=2199.11m$

Now displacement-

$\text{displacement}=\text{Final position - initial position}$

After $3.5$ round athelete will be at the opposite end of diameter.

So,

$\Rightarrow \text{displacement}=D$

$\Rightarrow \text{displacement}=200m$