Chapter 4.3, Problem 30E

(a)

To determine

The time at which the particle’s velocity is 0.

Answer to Problem 30E

  $t=-0.2$ , $t=4$ , and $t=12$

Explanation of Solution

Given information:

  

Concept used:

The velocity of the particle will be 0 at the point where the tangent on the graph of the position velocity is horizontal.

Calculation:

It is observed from the graph of the position velocity that at points $t=-0.2$ , $t=4$ , and $t=12$ , the tangents will be horizontal. So, this implies that the velocity of the particle will be 0 at $t=-0.2$ , $t=4$ , and $t=12$ .

(b)

To determine

The time at which the particle’s acceleration is 0.

Answer to Problem 30E

  $t=1.5$ , $t=5.2$ , $t=8$ , $t=11$ , and $t=13$

Explanation of Solution

Given information:

  

Concept used:

The acceleration of the particle will be 0 at the point where the concavity of the graph changes. In more simple words, it can be said that the acceleration of the particle will be 0 at the inflection point of the graph.

Calculation:

It is observed from the given graph that at points $t=1.5$ , $t=5.2$ , $t=8$ , $t=11$ , and $t=13$ , the concavity of the graph changes. So, this implies that the acceleration of the particle will be 0 at $t=1.5$ , $t=5.2$ , $t=8$ , $t=11$ , and $t=13$ .