Chapter 2.3, Problem 20PP

(a)

To determine

The time for which J had walked when H started walking.

Explanation of Solution

Introduction:

In a position time graph the position is plotted on the y axis and the time in the axis. The slope of the graph gives us the velocity.

From graph,

On the x axis, every small unit is $\text{0}\text{.1 h}$ . The x intercept for the H line is $\text{0}\text{.1 h}$ . This is the time for which J has walked.

Conclusion:

The time for which J had walked when Hstarted walking is $\text{0}\text{.1 h}$ .

(b)

To determine

Whether H meets J.

Explanation of Solution

Introduction:

In a position time graph, the position is plotted on the y axis and the time in the axis. The slope describes the velocity. If the graph is a straight line, then the velocity is constant.

The slope of a position time graph describes the velocity. The steeper the line, greater is the velocity. From the graph, J’s slope is steeper than H’s therefore Hwill not catch up J.

Conclusion:

J’s slope is steeper than H’s therefore H will not catch up J.

(c)

To determine

Position of J at $t\text{=0}\text{.2 h}$

Explanation of Solution

Introduction:

In a position time graph, the position is plotted on the y axis and the time in the axis. The slope describes the velocity. If the graph is a straight line, then the velocity is constant.

On the x axis every small unit is $\text{0}\text{.1 h}$ and on axis, every small unit is $\text{1 km}$ .

From the graph, in J’s line the corresponding value of position for $t\text{=0}\text{.2 h}$ is $\text{1 km}$ .

Conclusion:

Position of Juanita at $t\text{=0}\text{.2 h}$ is $\text{1 km}$ .

(d)

To determine

Time of Heather when his position is at 5 km.

Explanation of Solution

Introduction:

In a position time graph, the position is plotted on the y axis and the time in the axis. The slope describes the velocity. If the graph is a straight line, then the velocity is constant.

On the x axis, every small unit is $\text{0}\text{.1 h}$ and on y axis, every small unit is $\text{1 km}$ .

From the graph, in H’s line the corresponding value of time for position at $\text{5 km}$ is $\text{1}\text{.8 h}$ .

Conclusion:

The time when Heather is $\text{5 km}$ from the start is $\text{1}\text{.8 h}$ .