Motion and Time Class 7 Notes: CBSE Science Chapter 9

Motion

• The movement of an object or the tendency of an object to move from its place with respect to time is called motion 

• For example Movement of the pendulum of a clock is a motion, falling of leaves from trees is a motion etc.

There are Two Types of Motions 

1. Uniform Motion: If an object moves in a straight line at a constant speed i.e., speed is not changing over time, then the motion is uniform motion.

2. Non-Uniform Motion: If an object moves in a straight line and the speed of an object changes over time, then the motion is a non-uniform motion.

Speed

• The distance covered by an object per unit time is called speed. Thus, $S=\dfrac{D}{T}$  where $S$ represent the speed of an object, $D$ represent the distance covered by an object and $T$ represent the time taken by the object.

• SI unit of speed is $m/s$.

Measurement of Time

• In earlier periods, the shadow of objects cast by the sun was used to measure time.

• Simple Pendulum: It is a type of clock used to measure time and is the best example of periodic motion.

• Periodic or oscillatory motion is the to and fro movement of an object.

• Oscillation: The process of moving back and forth.

• The time taken by the pendulum to complete one complete oscillation is called the time period.

• The basic or SI unit of time is seconds denoted by $s$

Measuring Speed:

• Speedometer: It is a device used to measure the speed of a vehicle is $Km/hr$ 

• Odometer: It is a device used to measure the distance covered by a vehicle.

Distance-Time Graph

• It is used to study the motion of an object. 

• The distance is represented on the Y-axis and time is represented on the X-axis.

• The motion is uniform when the distance-time graph is a straight line.

• If the distance-time graph is moving upwards then the speed of the object is increasing. 

• If the distance-time graph is moving downwards then the speed of an object is decreasing

• The object is said to be at rest if the distance-time graph is parallel to the X-axis.

• The object's speed is determined by the slope of the distance-time graph.

• If there is a curve in the distance-time graph then the speed of the object is changing.

Important Topics of Class 7 Chapter 9 Science You Shouldn’t Miss!

Here are the important topics of Class 7 Science Chapter 9 Motion and Time that you shouldn't miss:

1. Types of Motion:

• Rectilinear Motion: Motion in a straight line.

• Circular Motion: Motion along a circular path.

• Periodic Motion: Motion that repeats at regular intervals.

2. Speed and Velocity:

• Speed: Distance traveled per unit time. Formula: \[ \text{Speed} = \frac{\text{Distance}}{\text{Time}} \].

• Velocity: Speed with a direction. Formula: \[ \text{Velocity} = \frac{\text{Displacement}}{\text{Time}} \].

3. Measurement of Time:

• Different instruments used for measuring time, such as clocks and stopwatches.

• Understanding the concept of time units and conversion between them.

4. Distance-Time Graphs:

• How to plot and interpret distance-time graphs to understand motion.

• Different types of graphs representing uniform and non-uniform motion.

5. Uniform and Non-Uniform Motion:

• Uniform Motion: When an object covers equal distances in equal intervals of time.

• Non-Uniform Motion: When an object covers unequal distances in equal intervals of time.

Importance of Science Chapter 9 Class 7 Motion and Time Notes

1. Foundation of Motion Concepts: They provide a fundamental understanding of different types of motion, such as rectilinear, circular, and periodic, which are essential for grasping more advanced concepts in later studies.

2. Understanding Speed and Velocity: Class 7 Science Chapter Motion And Time Notes help clarify the difference between speed and velocity, including their calculations and applications, which are crucial for analysing motion.

3. Practical Measurement Skills: They cover methods for measuring time and distance, using various instruments like clocks and stopwatches, which are practical skills applicable in real-life scenarios.

4. Graphical Interpretation: The notes explain how to interpret distance-time, helping in the visualisation of motion and understanding how to analyse data graphically.

5. Conceptual Clarity: By breaking down concepts such as uniform and non-uniform motion and relative motion, Motion And Time Notes Class 7 PDF enhances students' conceptual clarity and problem-solving skills.

6. Exam Preparation: Well-organised notes provide a structured summary of key topics, making it easier to review and prepare for exams.

Tips for Learning the Class 7 Science Chapter 9 Motion and Time

• Start with the basics of motion, including types and key terms.

• Memorise and practice using formulas for speed, velocity, and distance.

• Use diagrams and graphs to visualise motion and interpret data.

• Conduct simple experiments to measure and observe motion.

• Solve various practice problems to apply what you've learned.

• Use flashcards and educational videos for additional study material.

• Review key topics regularly to reinforce your understanding.

Conclusion

Class 7 Science Chapter Motion And Time Notes provide a clear understanding of key concepts related to motion and the measurement of time. By exploring different types of motion and how we use clocks and calendars, students can see the importance of these topics in everyday life. The notes are designed to help with quick revision and exam preparation, making it easier for students to grasp these essential ideas. With regular study and practice, students will feel confident in their knowledge of motion and time.

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