Chapter 2.1, Problem 4PP

To determine

To calculate: the time taken by the runner to travel 1 km.

Answer to Problem 4PP

The required time taken by the runner is

  $\boxed{t=200\text{s}}$ .

Explanation of Solution

Given:

The speed is $s=5\text{m/s}$ .

The distance is $d=1\text{km}$ .

Formula used:

The expression of speed is

  $s=\frac{d}{t}$....................(1)

Here, $d$ and $t$ are distance and time respectively.

Calculation:

Equation (1) can be rearranged as,

  $t=\frac{d}{s}$....................(2)

Substitute $1\text{km}$ for $d$ and $5\text{m/s}$ for $s$ in equation (1)

  $\begin{array}{l}t=\frac{1\text{km}}{5\text{m/s}}\\ t=\frac{1\text{km}\times \frac{1000\text{m}}{1\text{km}}}{5\text{m/s}}\\ t=\frac{1000\text{m}}{5\text{m/s}}\\ \boxed{t=200\text{s}}\end{array}$

Conclusion:

Hence, the required time taken by the runner is $\boxed{t=200\text{s}}$ .