Chapter 2, Problem 9STP

To determine

To Choose:The correct option.

Answer to Problem 9STP

A correct answer is an option (B).

Explanation of Solution

Given:

The given table is shown below

Runner	Distance covered (km)	Time (min)
Ling-Long	12.5	42
LaToya	7.8	38
Bill	10.5	32
Jose	8.9	30

Formula used:

The average speed is

  $s=\frac{d}{t}$  ...... (1)

Here, $d$ and $t$ are distance and time taken to travel.

Momentum can be written as

  $p=mv$  ...... (2)

Here, $m$ and $v$ are mass and speed.

Calculation:

Substitute 12.5 km for $d$ and 42 min for $t$ in equation (1) for Ling-Ling’s average speed

  $\begin{array}{l}s=\frac{12.5\text{km}}{42\min }\\ \boxed{s=0.30\text{km/min}}\end{array}$

Substitute 7.80 km for $d$ and 38 min for $t$ in equation (1) for LaToya’s average speed

  $\begin{array}{l}s=\frac{7.8\text{km}}{38\min }\\ \boxed{s=0.20\text{km/min}}\end{array}$

Substitute 10.5 km for $d$ and 32 min for $t$ in equation (1) for Bill’s average speed

  $\begin{array}{l}s=\frac{10.5\text{km}}{32\min }\\ \boxed{s=0.33\text{km/min}}\end{array}$

Substitute 8.9 km for $d$ and 30 min for $t$ in equation (1) for Jose’s average speed

  $\begin{array}{l}s=\frac{8.9\text{km}}{30\min }\\ \boxed{s=0.30\text{km/min}}\end{array}$

From equation (1), it can be observed that speed is directly proportional to the momentum, therefore, lesser speed smaller would be the momentum. From the above calculation, it is evident that LaToya has smallest momentum.

Conclusion:

Hence,LaToya has smallest momentum.