Velocity Acceleration Fcb987
1. **Problem Statement:**
We are given the position function $s(t)$ of a car along a straight road and asked to identify which graph (A-F) best represents the derivative of the velocity function $v'(t)$, where $v(t) = s'(t)$ is the velocity.
2. **Understanding the Functions:**
- $s(t)$ is the position function (in thousands of feet).
- $v(t) = s'(t)$ is the velocity function (rate of change of position).
- $v'(t)$ is the acceleration function (rate of change of velocity).
3. **Key Concepts:**
- The derivative of position $s(t)$ is velocity $v(t)$.
- The derivative of velocity $v(t)$ is acceleration $v'(t)$.
- When $v'(t)$ is positive, velocity is increasing (car speeding up).
- When $v'(t)$ is negative, velocity is decreasing (car slowing down).
- The position graph $s(t)$ is stepwise increasing with flat sections and sharp rises, so velocity $v(t)$ is zero during flat sections and positive during sharp rises.
4. **Analyzing the Graphs:**
- Since $s(t)$ has flat sections, $v(t)$ is zero there, so $v'(t)$ should be zero or near zero during those times.
- Sharp rises in $s(t)$ correspond to positive velocity spikes.
- The acceleration $v'(t)$ should show spikes at the points where velocity changes abruptly.
5. **Selecting the Best Graph:**
- Graph B shows positive and negative spikes crossing zero frequently, matching the sudden changes in velocity.
- Other graphs either show continuous oscillations or only positive values, which do not fit the stepwise nature of $s(t)$.
6. **Evaluating the Statements:**
- A. False. $v'(t)$ negative means velocity is decreasing, not necessarily moving backwards.
- B. False. The statement is self-contradictory.
- C. True. Negative $v'(t)$ means slowing down.
- D. False. $v'(t)$ is acceleration, not position.
- E. True. Velocity can be nonzero when acceleration is zero.
- F. True. $v'(t)$ represents acceleration.
- G. False. Zero acceleration does not imply zero velocity.
- H. False. Some statements are true.
**Final answers:**
- Best graph representing $v'(t)$ is **Graph B**.
- True statements: **C, E, F**.