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NCERT books contain a variety of questions given at the end of each chapter which are based on every conceptual topic. Students must solve all these NCERT questions to keep a track of their understanding. Practicing the NCERT questions will assure good results as most of the questions in annual examinations are asked from NCERT textbooks.
In this article we are providing NCERT Solutions for Class 9 Science Chapter 8 - Motion. Prepared by the subject matter experts, these solutions will help you get the right approach to all the NCERT questions and clear your concepts.
Students may download the NCERT solutions for Class 9 Science chapter - Motion, in the form of PDF.
Main topics discussed in Class 9 Science chapter- Motion are:
- Motion along a straight line
- Uniform motion and non-uniform motion
- Measuring the rate of motion
- Speed with direction
- Rate of change of velocity
- Graphical representation of motion
- Equations of motion by graphical method
- Equation for velocity-time relation
- Equation for position-time relation
- Equation for position–velocity relation
- Uniform circular motion.
Some of the questions and their solutions from NCERT Solutions for Class 9: Motion, are as follows:
Q. An object has moved through a distance. Can it have zero displacement? If yes, support your answer with an example.
Sol.
Yes, an object which has moved through a distance can have zero displacement, if it returns to its initial position after covering the desired distance.
For example: If a boy starts from his home goes to the market and then returns back to home, then his displacement is zero as the initial and the final position are the same which in this case is the home.
Q. Under what condition(s) is the magnitude of average velocity of an object equal to its average speed?
Sol.
The magnitude of average velocity is equal to the average speed when a body moves in a straight line.
Q. When will you say a body is in:
(i) Uniform acceleration?
(ii) Non-uniform acceleration?
Sol.
(i) A body has uniform acceleration, if its velocity changes by equal amount in equal interval of time.
(ii) A body has non-uniform acceleration, if its velocity changes by unequal amount in equal interval of time.
Q. What is the nature of the distance-time graphs for uniform and non-uniform motion of an object?
Sol.
(i) For uniform motion of an object, its distance-time graph is a straight line with constant slope.
(ii) For non-uniform motion of an object, its distance-time graph is a curved line with increasing or decreasing slope.
Q. State which of the following situations are possible and give an example for each of these:
(a) An object with a constant acceleration but with zero velocity.
(b) An object moving in a certain direction with acceleration in the perpendicular direction.
Sol.
(a) When an object is thrown vertically upward, then at highest point its velocity is zero but it has constant acceleration of 9.8 ms–2 which is termed as acceleration due to gravity.
(b) An aeroplane flies in horizontal direction but the acceleration due to gravity acts on it in vertically downward direction i.e., along the direction perpendicular to the direction of motion.
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