Speed and Velocity MCQs Quiz | Class 9
Test your understanding with this Speed and Velocity MCQs Quiz for Class 9 Science (Code 086), covering Unit III: Motion, Force and Work. The questions focus on definitions, SI units, and the differences between average and instantaneous speed. Submit your answers to view definitions and download the full PDF solution for exam preparation.
Understanding Speed and Velocity
In the study of Motion (Unit III), distinguishing between speed and velocity is fundamental. While both describe how fast an object moves, they differ significantly in their nature.
1. Speed
Speed is defined as the distance traveled by an object per unit time. It is a scalar quantity, meaning it has only magnitude and no specific direction. The SI unit of speed is meters per second (m/s).
- Average Speed: Total distance traveled divided by the total time taken.
- Instantaneous Speed: The speed of an object at a specific instant of time (measured by a speedometer).
2. Velocity
Velocity is the displacement of an object per unit time. It is a vector quantity, possessing both magnitude and direction. A change in either speed or direction results in a change in velocity.
| Feature | Speed | Velocity |
|---|---|---|
| Definition | Distance / Time | Displacement / Time |
| Quantity Type | Scalar | Vector |
| Value | Always positive (or zero) | Can be positive, negative, or zero |
3. Key Formulas
- Speed = Distance / Time
- Velocity = Displacement / Time
- Average Speed = Total Distance / Total Time
Quick Revision List
- The speedometer of a car measures instantaneous speed.
- The odometer measures the total distance traveled.
- If a body returns to its starting point, its average velocity is zero because displacement is zero.
- Uniform circular motion is an accelerated motion because the direction of velocity changes constantly.
Extra Practice Questions
- A car travels 100 meters in 5 seconds. What is its speed? (Ans: 20 m/s)
- Can a body have constant speed but varying velocity? (Ans: Yes, e.g., circular motion)
- What does the slope of a distance-time graph represent? (Ans: Speed)
- Convert 36 km/h into m/s. (Ans: 10 m/s)
- Is it possible to have zero speed but non-zero velocity? (Ans: No)
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