Force and Motion MCQs Quiz | Class 9
Test your understanding of Class IX Science (Code 086), Unit III: Motion, Force and Work. This quiz covers the effect of force on motion, change in state, and practical examples like inertia and balanced forces. Attempt these 10 multiple-choice questions, check your score, and download the solution PDF for revision.
Unit III: Motion, Force and Work – Overview
Force is an external effort in the form of a push or a pull that changes or tends to change the state of rest or of motion of an object, or its direction or dimensions. In Class 9 Science, understanding the nature of force and its effects is crucial for mastering mechanics.
1. Effects of Force
A force acting on an object can cause several effects:
- Change in Speed: It can make a stationary object move or change the speed of a moving object.
- Change in Direction: It can change the direction of motion of a moving object.
- Change in Shape: It can change the shape or size of an object (e.g., squeezing a rubber ball).
2. Balanced and Unbalanced Forces
| Balanced Forces | Unbalanced Forces |
|---|---|
| Resultant force is zero. | Resultant force is not zero. |
| Do not change the state of rest or motion. | Change the state of rest or motion. |
| Example: Pushing a heavy wall that does not move. | Example: Pushing a toy car to make it move. |
3. Newton’s First Law of Motion
Also known as the Law of Inertia, it states that an object remains in a state of rest or of uniform motion in a straight line unless compelled to change that state by an applied force.
4. Inertia and Mass
Inertia is the natural tendency of an object to resist a change in its state of motion or of rest. The mass of an object is a measure of its inertia. Heavier objects have more inertia than lighter objects.
- Inertia of Rest: A passenger falls backward when a bus starts suddenly.
- Inertia of Motion: A passenger falls forward when a moving bus stops suddenly.
- Inertia of Direction: A passenger leans sideways when a bus takes a sharp turn.
Extra Practice Questions
- What is the CGS unit of force? (Answer: Dyne)
- Why does a luggage on the roof of a bus need to be tied with a rope? (Answer: To prevent it from falling due to inertia)
- If no external force acts on a moving body, how long will it continue to move? (Answer: Forever, due to inertia)
- What force opposes the motion of a ball rolling on the ground? (Answer: Friction)
- Can balanced forces change the shape of an object? (Answer: Yes, e.g., squeezing a balloon)
Content created and reviewed by the CBSE Quiz Editorial Team based on the latest NCERT textbooks and CBSE syllabus. Our goal is to help students practice concepts clearly, confidently, and exam-ready through well-structured MCQs and revision content.