This graph illustrates a vehicle's speed over 50 seconds, divided into four distinct phases of acceleration and constant velocity.

- The graph shows speed versus time, divided into four segments: A (0-10 s), B (10-20 s), C (20-30 s), and D (30-50 s).
- Segment A: Speed increases uniformly from 0 to 15 m/s over 10 seconds. Acceleration = (15 - 0)/10 = 1.5 m/s².
- Segment B: Speed is constant at 15 m/s for 10 seconds. Acceleration = 0 m/s².
- Segment C: Speed increases uniformly from 15 to 25 m/s over 10 seconds. Acceleration = (25 - 15)/10 = 1.0 m/s².
- Segment D: Speed decreases uniformly from 25 to 0 m/s over 20 seconds. Acceleration = (0 - 25)/20 = -1.25 m/s².
- The total distance traveled is the area under the entire graph:
- Area A (triangle): (1/2) × 10 × 15 = 75 m.
- Area B (rectangle): 10 × 15 = 150 m.
- Area C (trapezoid): (1/2) × (15 + 25) × 10 = 200 m.
- Area D (triangle): (1/2) × 20 × 25 = 250 m.
- Total distance = 75 + 150 + 200 + 250 = 675 m.
- The average speed over the entire journey is total distance divided by total time: 675 m / 50 s = 13.5 m/s.