Question 13
A girl is preparing for her first marathon by running on a straight road. She uses a smartwatch to calculate her running speed at different intervals. The graph (Fig. 4.31) depicts her velocity versus time. Estimate the distance covered by her based on the graph.
Solution
Distance covered = Area under the Velocity-Time Graph
| Time Interval (h) | Velocity (km h⁻¹) | Distance (km) |
|---|---|---|
| 0 – 2 | 7 to 7.5 | ((7 + 7.5)/2) × 2 = 14.5 |
| 2 – 4 | ≈ 7.5 | 7.5 × 2 = 15 |
| 4 – 6 | 7.5 to 6.5 | ((7.5 + 6.5)/2) × 2 = 14 |
| 6 – 7 | 6.5 to 6 | ((6.5 + 6)/2) × 1 = 6.25 |
Total Distance Covered
= 14.5 + 15 + 14 + 6.25
= 49.75 km
≈ 50 km
Answer: The girl covers approximately 50 km.
