Question

Section 11.2 Speed and Velocity
(pages 332–337)
This section defines and compares speed and velocity. It also describes how to
calculate average speed.
Reading Strategy (page 332)
Monitoring Your Understanding After you read this section, identify
several things you have learned that are relevant to your life. Explain
why they are relevant to you. For more information on this Reading
Strategy, see the Reading and Study Skills in the Skills and
Reference Handbook at the end of your textbook.
Facts About Speed and Velocity
What Is Important
Why It Is Important
Speed (pages 332–334)
1. Define speed.
2. The SI units for speed are
.
3. How is instantaneous speed different from average speed?
4. The equation used for calculating average speed is
.
5. Is the following sentence true or false? You can determine how fast
you were going at the midpoint of a trip by calculating average
speed for the entire trip.
6. A student walked 1.5 km in 25 minutes, and then, realizing he was
late, ran the remaining 0.5 km in 5 minutes. Calculate his average
speed on the way to school.
7. What type of speed does an automobile’s speedometer display?
Graphing Motion (page 334)
8. The slope of a line on a distance-time graph represents
.

Answer 1

Reading strategy — Monitoring your understanding
- Things I learned that are relevant to my life:
1. Difference between average and instantaneous speed — helps me understand why a car’s speedometer (instantaneous) can show a different value than the average speed shown on a trip odometer or navigation app.
2. Average speed formula (total distance ÷ total time) — useful for planning travel time and estimating arrival times.
3. Interpreting distance–time graphs (slope = speed) — useful for reading motion data from fitness trackers or vehicle logs.

Facts About Speed and Velocity — brief summary
- What is important: definitions (speed vs velocity), SI unit, average speed formula, instantaneous vs average, slope of distance–time graph.
- Why it is important: allows calculation of travel times, understanding motion graphs, following speed limits, and comparing motions in everyday situations.

Answers to numbered questions
1. Define speed.
- Speed is the rate at which an object covers distance; a scalar quantity equal to distance traveled per unit time.

2. The SI units for speed are
- meters per second (m/s).

3. How is instantaneous speed different from average speed?
- Instantaneous speed is the speed at a specific moment in time; average speed is total distance traveled divided by total time for the whole trip.

4. The equation used for calculating average speed is
- average speed = total distance ÷ total time (v_avg = d_total / t_total).

5. Is the following sentence true or false? You can determine how fast you were going at the midpoint of a trip by calculating average speed for the entire trip.
- False. Average speed does not give the instantaneous speed at a specific point.

6. A student walked 1.5 km in 25 minutes, and then, realizing he was late, ran the remaining 0.5 km in 5 minutes. Calculate his average speed on the way to school.
- Total distance = 1.5 + 0.5 = 2.0 km. Total time = 25 + 5 = 30 min = 0.5 h.
- Average speed = 2.0 km / 0.5 h = 4.0 km/h.
- In SI units: 2000 m / 1800 s ≈ 1.11 m/s.

7. What type of speed does an automobile’s speedometer display?
- Instantaneous speed.

8. The slope of a line on a distance-time graph represents
- speed (rate of motion).