This TNPSC Physics Motion Test 3 is designed to help you confidently practice the Speed and Velocity concepts that are important for the TNPSC General Science syllabus. This Test includes physics questions on scalar and vector quantities, SI units, average speed, average velocity, uniform and non-uniform motion, direction of motion, speedometer, circular motion, and velocity in round trips. Take this TNPSC free test to check your preparation, strengthen your understanding of motion, and improve your performance in the exam.
Note: A detailed explanation for all questions is provided below the Test, helping you understand the concept clearly and improve your any TNPSC exam preparation.
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Detailed Explanations For All Test Questions – TNPSC Physics Motion Test 3
n this section, each question is explained in a simple and exam-oriented way, covering scalar and vector quantities, SI units, average speed, average velocity, uniform and non-uniform motion, direction of motion, speedometer readings, circular motion, and velocity in round trips. These detailed explanations will help you understand the concepts clearly, avoid common mistakes, and improve your accuracy in the TNPSC examination.
1. Speed is defined as the
Correct answer: B. Distance travelled per unit time
Speed is the distance travelled by an object in a given interval of time. It is a scalar quantity, which means it has only magnitude and no direction. The SI unit of speed is metre per second (m/s). In TNPSC Physics Motion questions, remember that speed depends only on the total distance travelled, not on the direction of motion.
Points To Remember:
- Speed = Distance travelled / Time taken
- Speed is a scalar quantity.
- The SI unit of speed is m/s.
2. Velocity is defined as the
Answer: B. Displacement per unit time in a specified direction
Velocity is the rate of change of displacement with respect to time. Unlike speed, velocity is a vector quantity because it has both magnitude and direction. An object can have the same speed but different velocities if its direction changes. In TNPSC Physics Motion questions, understanding the difference between speed and velocity is very important.
Points To Remember:
- Velocity = Displacement / Time
- Velocity is a vector quantity.
- Velocity includes both magnitude and direction.
- The SI unit of velocity is m/s.
3. Which of the following is a scalar quantity?
Answer: C. Speed
A scalar quantity has only magnitude and no direction. Speed is a scalar quantity because it tells us how fast an object moves without indicating the direction of motion. In contrast, velocity, acceleration, and force are vector quantities because they have both magnitude and direction. Questions based on scalar and vector quantities are common in TNPSC Physics Motion topics.
Points To Remember:
- Scalar quantities have only magnitude.
- Vector quantities have both magnitude and direction.
- Speed is a scalar quantity.
- Velocity, acceleration, and force are vector quantities.
4. Which of the following is a vector quantity?
Answer: D. Velocity
A vector quantity has both magnitude and direction. Velocity is a vector quantity because it describes the displacement of an object in a particular direction per unit time. Distance, speed, and time are scalar quantities because they do not include direction. In TNPSC Physics Motion questions, identifying scalar and vector quantities is an important basic concept.
Points To Remember:
- Vector quantities have both magnitude and direction.
- Velocity is a vector quantity.
- Distance, speed, and time are scalar quantities.
- The SI unit of velocity is m/s.
5. The SI unit of speed is
Answer: C. m/s
The SI unit of speed is metre per second (m/s). Speed is the distance travelled by an object per unit time, and in the International System of Units (SI), distance is measured in metres and time is measured in seconds. TNPSC often asks direct questions on SI units in the Motion topic.
Points To Remember:
- SI unit of speed = metre per second (m/s)
- Speed = Distance / Time
- Distance is measured in metres (m).
- Time is measured in seconds (s).
6. The SI unit of velocity is
Answer: B. m/s
The SI unit of velocity is metre per second (m/s). Velocity is the displacement of an object per unit time in a specified direction. Although speed and velocity have the same SI unit, velocity is a vector quantity because it includes direction.
Points To Remember:
- SI unit of velocity = metre per second (m/s)
- Velocity = Displacement / Time
- Velocity includes direction.
- Velocity is a vector quantity.
7. Which quantity includes both magnitude and direction?
Answer: C. Velocity
A quantity that has both magnitude and direction is called a vector quantity. Velocity is a vector quantity because it represents the displacement of an object in a particular direction per unit time. Speed, distance, and time do not include direction and are therefore scalar quantities.
Points To Remember:
- Vector quantities have both magnitude and direction.
- Velocity is a vector quantity.
- Speed, distance, and time are scalar quantities.
- Direction is the main feature that distinguishes velocity from speed.
8. Which quantity has only magnitude?
Answer: D. Speed
A quantity that has only magnitude and no direction is called a scalar quantity. Speed is a scalar quantity because it tells us how fast an object moves without specifying the direction of motion. Velocity, displacement, and acceleration are vector quantities because they include direction.
Points To Remember:
- Scalar quantities have only magnitude.
- Speed is a scalar quantity.
- Velocity, displacement, and acceleration are vector quantities.
- Speed does not include the direction of motion.
9. Average speed is calculated by
Answer: B. Total distance / total time
Average speed is the total distance travelled by an object divided by the total time taken. It considers the entire path covered during the motion, regardless of the direction of travel. Average speed helps describe how fast an object moves over a complete journey.
Points To Remember:
- Average Speed = Total Distance ÷ Total Time
- Speed is a scalar quantity and has only magnitude.
- The SI unit of average speed is metre per second (m/s).
- Distance travelled is always positive.
10. Average velocity is calculated by
Answer: B. Total displacement / total time
Average velocity is the total displacement of an object divided by the total time taken. Unlike average speed, average velocity depends on both magnitude and direction because displacement is a vector quantity. It represents the overall change in position of an object during motion.
Points To Remember:
- Average Velocity = Total Displacement ÷ Total Time
- Velocity is a vector quantity and has both magnitude and direction.
- The SI unit of average velocity is metre per second (m/s).
- If the displacement is zero, the average velocity is zero even when distance has been travelled.
11. A car travels equal distances in equal intervals of time. The car is said to be moving with
Answer: C. Uniform speed
When an object travels equal distances in equal intervals of time, it is said to move with uniform speed. This means the speed remains constant throughout the journey. Uniform speed is a basic concept in motion and is frequently tested in TNPSC Physics questions.
Points To Remember:
- Equal distances are covered in equal intervals of time.
- The speed remains constant.
- Uniform speed is a scalar quantity.
- The direction of motion may or may not change.
12. A car travels unequal distances in equal intervals of time. The car is said to be moving with
Answer: B. Non-uniform speed
When an object travels unequal distances in equal intervals of time, it is said to move with non-uniform speed. This means the speed changes during the motion. Most vehicles in real-life traffic usually move with non-uniform speed because they accelerate, decelerate, and stop at different times.
Points To Remember:
- Unequal distances are covered in equal intervals of time.
- The speed changes during the motion.
- Non-uniform speed is also called variable speed.
- Non-uniform motion is common in everyday life.
13. Which of the following can change even when speed remains constant?
Answer: C. Direction of motion
An object can move with constant speed while changing its direction of motion. When the direction changes, the velocity changes because velocity depends on both magnitude and direction. A common example is circular motion, where speed may remain constant but the direction changes continuously.
Points To Remember:
- Speed depends only on magnitude.
- Velocity depends on both magnitude and direction.
- A change in direction changes the velocity.
- Circular motion involves continuous change in direction.
14. A train moving eastward at 20 m/s is described by its
Answer: C. Velocity
Velocity describes both the magnitude and the direction of motion. The statement “20 m/s eastward” includes the speed (20 m/s) and the direction (eastward), so it represents velocity. In TNPSC Physics Motion questions, any quantity that includes direction is treated as a vector quantity.
Points To Remember:
- Velocity includes both magnitude and direction.
- “20 m/s eastward” is a vector quantity.
- Speed gives only magnitude.
- The SI unit of velocity is m/s.
15. Which instrument is commonly used to measure the speed of a vehicle?
Answer: C. Speedometer
A speedometer is used to measure the instantaneous speed of a moving vehicle. It shows how fast the vehicle is moving at a particular moment. An odometer measures the total distance travelled, while a stopwatch measures time. Questions on measuring instruments are common in TNPSC Physics Motion topics.
Points To Remember:
- A speedometer measures the speed of a vehicle.
- An odometer measures the distance travelled.
- A stopwatch measures time.
- Speed is usually displayed in km/h or m/s.
16. Which of the following statements is correct regarding speed and velocity?
Answer: D. Speed is scalar, whereas velocity is vector.
Speed is a scalar quantity because it has only magnitude. Velocity is a vector quantity because it has both magnitude and direction. This is one of the most important concepts in TNPSC Physics Motion and is frequently tested in objective questions.
Points To Remember:
- Speed has only magnitude.
- Velocity has both magnitude and direction.
- Speed is a scalar quantity.
- Velocity is a vector quantity.
17. A runner completes one full circular track and returns to the starting point. The average velocity is
Answer: C. Zero
Average velocity is calculated by dividing total displacement by total time. When the runner returns to the starting point after completing one full circular track, the initial and final positions are the same. Therefore, the displacement is zero, and the average velocity is also zero.
Points To Remember:
- Average Velocity = Total Displacement / Total Time
- Displacement is zero after one complete round trip.
- Average velocity becomes zero when displacement is zero.
- This is a common TNPSC concept in circular motion.
18. A runner completes one full circular track and returns to the starting point. The average speed is
Answer: B. Total distance travelled divided by total time
Average speed is calculated by dividing the total distance travelled by the total time taken. Even though the runner returns to the starting point, the distance travelled is equal to the circumference of the circular track. Therefore, the average speed is not zero.
Points To Remember:
- Average Speed = Total Distance / Total Time
- Distance travelled in one complete circular track is the circumference.
- Average speed is always based on distance, not displacement.
- Average speed is usually not zero in a round trip.
19. Which quantity can be zero even when an object has travelled a certain distance?
Answer: C. Average velocity
Average velocity depends on the total displacement of an object, not on the total distance travelled. An object may travel a certain distance and return to its starting point, making the displacement zero. In that case, the average velocity becomes zero even though distance has been travelled.
Points To Remember:
- Average Velocity = Total Displacement / Total Time
- Average velocity can be zero when displacement is zero.
- Distance travelled may still be greater than zero.
- This commonly occurs in round trips and circular motion.
20. Which of the following statements correctly distinguishes speed and velocity?
Answer: B. Velocity depends on direction, whereas speed does not.
Speed is a scalar quantity because it has only magnitude, while velocity is a vector quantity because it has both magnitude and direction. Two objects may have the same speed but different velocities if they move in different directions. This distinction is one of the most important concepts in TNPSC Physics Motion.
Points To Remember:
- Speed has only magnitude.
- Velocity has both magnitude and direction.
- Speed is a scalar quantity.
- Velocity changes if the direction of motion changes.
Speed vs Velocity: Quick Comparison for TNPSC Aspirants
| Speed | Velocity |
|---|---|
| Distance travelled per unit time | Displacement per unit time |
| Scalar quantity | Vector quantity |
| Has only magnitude | Has magnitude and direction |
| Direction is not required | Direction is essential |
| Cannot be negative in ordinary motion | Can be positive, negative, or zero depending on direction |
| Formula: Distance / Time | Formula: Displacement / Time |
| Example: 20 m/s | Example: 20 m/s eastward |
- Speed is a scalar quantity.
- Velocity is a vector quantity.
- In a round trip, average speed is not zero, but average velocity can be zero.
Reference material – Motion
For a better understanding of TNPSC Physics Motion, refer to the NCERT Class 9 Science chapter “Describing Motion Around Us.” This chapter covers distance and displacement, speed and velocity, scalar and vector quantities, SI units, and different types of motion, making it a useful reference for TNPSC Physics, General Science, and TNPSC exam preparation.
