Question: Jadon decides to go for a run.
The graph on the right shows Jadon’s speed in metres per second ($s$) over time in seconds ($t$).
The gradient of the negative sloping section of the graph is $0.8$.
Which of the following does that $0.8$ best represent?
A
Jadon is travelling at a speed of $0.8$ m/s
B
Jadon is decelerating at a rate of $0.8$ m/s$^2$
C
Jadon is resting for $0.8$ seconds
D
Jadon is accelerating at a rate of $0.8$ m/s$^2$
1. **State the problem:** We are given a speed versus time graph for Jadon, with a negative slope section having a gradient of $0.8$. We need to interpret what this gradient represents.
2. **Recall the meaning of gradient in a speed-time graph:** The gradient of a speed-time graph represents acceleration (or deceleration) because acceleration is the rate of change of speed with respect to time.
3. **Analyze the gradient value:** The gradient is $0.8$ and the slope is negative (downward sloping), so the acceleration is negative, meaning Jadon is slowing down.
4. **Interpret the options:**
- Option A says Jadon is travelling at $0.8$ m/s, but the gradient is not speed, it is acceleration.
- Option B says Jadon is decelerating at a rate of $0.8$ m/s$^2$, which matches the negative slope and gradient magnitude.
- Option C says Jadon is resting for $0.8$ seconds, which is unrelated to the gradient.
- Option D says Jadon is accelerating at $0.8$ m/s$^2$, but the slope is negative, so acceleration is negative, not positive.
5. **Conclusion:** The gradient $0.8$ best represents Jadon decelerating at a rate of $0.8$ m/s$^2$.
**Final answer:** Option B.