Grade 7
  1. Introduction to Physics  1.1. Definition and scope of physics  1.2. Importance of Physics in Daily Life and Technology  1.3. Scientific method and its applications in physics  1.4. Measurement and Experiments in Physics  1.5. Branches of Physics and their Applications  1.6. Relation of physics with other sciences
  2. Measurement and units  2.1. Fundamental and derived quantities  2.2. SI units and unit conversions  2.3. Length measuring instruments and tools used  2.4. Measuring the difference between mass and weight  2.5. Measuring time with accuracy  2.6. Measuring the Volume of Regular and Irregular Objects  2.7. Measuring Temperature and Temperature Scales  2.8. Accuracy, Precision, and Significant Figures  2.9. Errors in Measurement and How to Reduce Them  2.10. Estimates and approximations in scientific calculations  2.11. Standard form and order of magnitude
  3. Speed and Force  3.1. Introduction to motion and rest  3.2. Types of motion - uniform and non-uniform  3.3. Scalars and vectors in motion  3.4. Speed, Velocity, and Acceleration  3.5. Distance-time and velocity-time graphs  3.6. Newton's first law of motion (law of inertia)  3.7. Newton's second law of motion (force and acceleration)  3.8. newton's third law of motion  3.9. Types of forces - contact and non-contact forces  3.10. Effect of forces on motion  3.11. Friction – types, effects and applications  3.12. Gravity, free fall and gravitational acceleration  3.13. Circular motion and centripetal force  3.14. Application of Newton's laws in real life
  4. Energy, Work and Power  4.1. Definition and forms of energy  4.2. Potential and Kinetic Energy  4.3. Law of conservation of energy  4.4. Energy transformations in everyday life  4.5. Work done by force and its calculation  4.6. Power - Definition and Calculation  4.7. Simple Machines and Mechanical Advantage  4.8. Efficiency and energy losses of machines  4.9. Renewable and non-renewable energy sources
  5. Heat and temperature  5.1. Difference Between Heat and Temperature  5.2. Thermometer and temperature scale (Celsius, Kelvin, Fahrenheit)  5.3. Expansion and contraction of solids, liquids and gases  5.4. Heat transfer methods – conduction, convection and radiation  5.5. good and bad conductors of heat  5.6. Applications of heat transfer in daily life  5.7. Specific heat capacity and its applications  5.8. Latent heat and change of state  5.9. Thermal equilibrium and heat exchange  5.10. effect of heat on matter
  6. Lighting and Optics  6.1. Nature and properties of light  6.2. Reflection of light and laws of reflection  6.3. Image formation by plane and curved mirrors  6.4. Refraction of light and the laws of refraction  6.5. Lenses – convex and concave, image formation  6.6. Optical instruments – microscope, telescope, camera  6.7. Dispersion of light and formation of spectrum  6.8. Human eye, vision defects and their correction  6.9. Applications of optics in daily life  6.10. Total internal reflection and its applications
  7. Sound and waves  7.1. Nature and properties of waves  7.2. Production and propagation of sound  7.3. Characteristics of sound waves – frequency, amplitude, wavelength  7.4. Speed of sound in different mediums  7.5. Reflection of sound – echo and reverberation  7.6. Ultrasound and its applications  7.7. Doppler effect in sound waves  7.8. Noise pollution and its effects  7.9. Applications of sound in medicine and industry
  8. Electricity and Magnetism  8.1. Electric charge and static electricity  8.2. Electrical conductors and insulators  8.3. Electric current, voltage and resistance  8.4. Ohm's law and its applications  8.5. Electrical Circuits - Series and Parallel Circuits  8.6. Electric power and energy consumption  8.7. Safety precautions in the use of electricity  8.8. Properties of magnets and magnetic fields  8.9. Electromagnets - How They Work and Their Uses  8.10. Relation between electricity and magnetism (electromagnetic induction)  8.11. Applications of electromagnetism in technology  8.12. Earth's magnetic field and its effects
  9. Matter and its properties  9.1. Classification of matter- solid, liquid and gas  9.2. Properties of different states of matter  9.3. Kinetic theory of matter  9.4. Changes in the state of matter and their causes  9.5. Expansion and contraction of substances  9.6. Density and its calculation  9.7. Pressure in solids, liquids and gases  9.8. Atmospheric pressure and its effects  9.9. Applications of pressure in daily life  9.10. Buoyancy and Archimedes' principle
  10. Space Science and Solar System  10.1. Introduction to Astronomy  10.2. Solar System - Planets and their Characteristics  10.3. Sun - structure and energy production  10.4. Moon - phases and its effect on Earth  10.5. Rotation and revolution of the earth  10.6. Solar and lunar eclipses  10.7. Gravity in space and its role in orbits  10.8. Artificial satellites and their uses  10.9. Space exploration and modern discoveries  10.10. Asteroids, comets and meteors  10.11. Life beyond Earth - Possibilities and Theories
  11. Environmental Physics  11.1. Impact of physics on environmental science  11.2. Renewable and non-renewable energy sources  11.3. Energy conservation and efficiency  11.4. Climate change and its effects on Earth  11.5. Air, water and soil pollution – causes and effects  11.6. Greenhouse effect and global warming  11.7. Sustainable development and environmental protection  11.8. Role of Physics in Weather and Climate Studies

Grade 7 → Speed and Force ↓


Distance-time and velocity-time graphs


In the study of physics, especially aspects related to motion and forces, graphs play an important role in interpreting data and understanding the relationships between various physical quantities. Two very important graphs are distance-time graphs and velocity-time graphs. These graphs help us visualize and describe the motion of an object over time.

Distance-time diagram

A distance-time graph shows how distance changes over time. The x-axis of the graph usually represents time, while the y-axis represents distance. By looking at the slope of the graph, you can tell how fast an object is moving.

Basic features:

  • If the graph is a straight line that moves to the right, it means the object is moving at a constant speed.
  • If the line is horizontal, it indicates that the object is stationary, since time is passing but the distance is constant.
  • If the line turns upward, it indicates that the object is accelerating.
  • If the line curves downward, the object is slowing down.

Visual example:

Time distance

Example explanation:

Imagine you are going for a walk. You start walking and then walk at a constant speed. This is represented by the rising straight line at the beginning. Then, you stop to rest for some time. During this rest, a horizontal line appears in the graph. If you start walking again, but faster, you will see a sharp rise in the line.

Velocity-time graphs

A velocity-time graph shows how the velocity of an object changes over time. Just like a distance-time graph, the x-axis represents time, but the y-axis represents velocity.

Basic features:

  • The horizontal line shows that the object is moving at a constant velocity.
  • If the line is at zero then it indicates that the object is at rest.
  • The upward line indicates that the object is accelerating.
  • The downward moving line indicates that the object is slowing down.
  • The area under the curve in the velocity-time graph represents the distance travelled by the object.

Visual example:

Time Velocity

Example explanation:

Consider a car starting from rest. As the car accelerates, the velocity increases which is represented by an upward sloping line on the graph. If the car moves at a constant speed, the line becomes flat. If the driver applies the brakes, the velocity decreases which is represented by a downward slope.

Mathematical representation and computation

Graphs are not just about visual representation; they are also important for mathematical analysis. By examining the slope and the area under the curves, we can derive various quantities related to motion.

Slope of distance-time graph:

The slope of the distance-time graph gives the speed of the object. Mathematically:

    Slope = Speed = Change in Distance / Change in Time

For example, if you cover 100 meters in 20 seconds, your speed is:

    Speed = 100 meters / 20 seconds = 5 meters/second

Slope of velocity-time graph:

The slope of the velocity-time graph is the acceleration of the object:

    Acceleration = Change in Velocity / Change in Time

So, if a car accelerates from 0 to 60 m/s in 10 sec, then the acceleration will be:

    Acceleration = 60 m/s / 10 s = 6 m/s²

Area under the velocity-time graph:

The area under the velocity-time graph gives the total distance travelled by the object. For uniform motion, it can be calculated as follows:

    Distance = Velocity × Time

Real-world applications and context

Understanding these graphs is essential in various practical scenarios, such as analyzing the performance of vehicles, understanding the motion of celestial bodies, designing safer roads and transportation systems, etc.

Example: Traffic and road safety

Road safety experts often use distance-time and velocity-time graphs to understand and improve traffic systems. They can create better traffic signals, speed limits, and road designs by analyzing how vehicles move on the road.

Example: Sports and fitness

In sports, coaches use these graphs to track athletes' performance. By analyzing runners' speed and pace over time, coaches can create training programs that improve athlete performance.

Conclusion

Distance-time and velocity-time graphs are fundamental tools for depicting, visualizing, and analyzing motion in physics. By understanding how to interpret these graphs, you gain insight into the nature of motion, helping you apply these principles to real-world problems and scientific investigations. The simplicity and efficiency of these graphical methods provide a clear and visual path to understanding motion in a world governed by forces and momentum.


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Distance-time and velocity-time graphs

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