Uniform Circular Motion (Elementary) MCQs Quiz | Class 9
Test your understanding of Class IX Science (Code 086), Unit III: Motion, Force and Work. This quiz covers the meaning of uniform circular motion, real-life examples, and the concept of direction change. Answer the questions, submit to check your score, and download the solution PDF for revision.
Understanding Uniform Circular Motion
Uniform circular motion is a specific type of motion in which an object travels along a circular path at a constant speed. Although the speed remains the same, the velocity is constantly changing. This concept is fundamental to understanding motion in Class 9 Science.
Key Concepts
- Constant Speed: The object covers equal distances in equal intervals of time along the circular path.
- Variable Velocity: Since velocity is a vector quantity, it depends on both magnitude (speed) and direction. In circular motion, the direction of motion changes at every point. Therefore, the velocity is not constant.
- Accelerated Motion: Because the velocity changes continuously (due to direction change), uniform circular motion is always considered an accelerated motion.
- Direction of Motion: At any point on the circular path, the direction of motion is along the tangent to the circle at that point.
Examples in Daily Life
| Object | Motion Type | Explanation |
|---|---|---|
| Tip of a clock hand | Uniform Circular | Moves at constant speed but direction changes continuously. |
| Moon orbiting Earth | Uniform Circular (Approx) | Gravity acts as the force keeping it in orbit. |
| Athlete on circular track | Uniform Circular | Running at constant speed requires constant turning. |
Quick Revision Points
- If a stone tied to a string is whirled and the string breaks, the stone flies off tangentially.
- The force responsible for keeping an object in circular motion acts towards the center (centripetal force).
- One complete revolution brings displacement to zero, but distance traveled is 2 x pi x r.
Extra Practice Questions
- Q1: Is the motion of the earth around the sun uniform or non-uniform? (Ans: Uniform circular motion)
- Q2: Can a body have constant speed but varying velocity? (Ans: Yes, in circular motion)
- Q3: What is the direction of acceleration in uniform circular motion? (Ans: Towards the center)
- Q4: Does the speed change when an athlete runs on a circular track with uniform motion? (Ans: No)
- Q5: What happens to velocity if the radius of the circle increases while speed remains constant? (Ans: Velocity magnitude is same, direction change rate decreases)
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