Chapter 1, Problem 3STP

To determine

To Choose: The correct option.

Answer to Problem 3STP

Option B

Explanation of Solution

Given:

A quantity is given in m/s and another in km.

Final result is in seconds.

Formula Used:

Relation between meter and kilometre is as follows:

  $1\text{km =}1000\text{m}$

Calculations:

To achieve the result in seconds, one must divide the quantity given in km by the quantity given in m/s.

  $\frac{\text{km}}{\text{m/s}}=\frac{\text{km}}{\text{m}}\times \text{s}$

Now, one should multiply this quantity by 1000. This is because one needs to convert km to m, so that they cancel out and one is left with the quantity in seconds.

  $\begin{array}{l}\because 1\text{km =}1000\text{m}\\ \frac{\text{km}}{\text{m}}\times \text{s}=\frac{1000\text{m}}{\text{m}}\times \text{s}\end{array}$

Conclusion:

Thus, the correct option is B.