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 → Measurement and units ↓


Measuring the Volume of Regular and Irregular Objects


Volume is a measure of how much space an object occupies. Understanding volume in physics is essential because it helps us measure the amount of matter in physical space. In grade 7 physics, students learn about the basic techniques used to measure the volume of both regular and irregular objects.

Measuring the volume of regular objects

Regular objects are those that have a definite geometric shape. Examples include cubes, rectangular prisms, cylinders, spheres, and more. The key to measuring the volume of these objects is to use mathematical formulas derived from their geometric properties.

Volume of a cube

A cube has equal sides, so you can easily find its volume by measuring the length of one side and cubing it. The formula for a cube with side length s is:

Volume = s × s × s = s³

Suppose we have a cube with a side of 3 cm. The volume will be calculated as follows:

Volume = 3 cm × 3 cm × 3 cm = 27 cm³
S=3cm

Volume of a rectangular prism

A rectangular prism has different length, width, and height. The volume formula is:

Volume = length × width × height

For example, the volume of a prism with dimensions 4 cm (length), 3 cm (width) and 2 cm (height) will be:

Volume = 4 cm × 3 cm × 2 cm = 24 cm³
4cm x 3cm x 2cm

Volume of a cylinder

For a cylinder, the volume is calculated using the radius and height. The formula is:

Volume = π × radius² × height

Let's find the volume of a cylinder with a radius of 2 cm and a height of 5 cm:

Volume = π × (2 cm)² × 5 cm = π × 4 cm² × 5 cm = 20π cm³
r=2cm h=5cm

Measuring the volume of irregular objects

Irregular objects have no definite geometric shape, making them more challenging to measure directly. Instead, we use the water displacement method to determine their volume.

Water displacement method

The water displacement method involves submerging an object in water and measuring the amount of water it displaces. This method is based on Archimedes' principle, which states that the amount of water displaced by an object is equal to the volume of the object.

  1. Fill a graduated cylinder with a known quantity of water.
  2. Submerge the irregular object in the water. Make sure it is completely submerged.
  3. Record the new water level.
  4. Subtract the initial water volume from the new water volume to find the volume of the object.

Let's look at an example:

Initial water level: 50 ml
New water level: 70 ml
Volume of object = New water level - Initial water level = 70 ml - 50 ml = 20 ml
50 ml 70 ml

Using these techniques, you can easily measure the volume of both regular and irregular objects. Understanding these measurements is important for observing physical properties and engaging in a variety of scientific and engineering applications.

Practical considerations

When measuring volume, especially for irregular objects, be aware of the following potential challenges:

  • Make sure the item does not dissolve or react with water.
  • Make sure all air bubbles are removed when submerging the object in the water.

Sample practice

Let's practice some problems:

  1. Find the volume of a rectangular prism of dimensions 5 cm, 3 cm and 6 cm.
  2. Determine the volume of a sphere with a radius of 4 cm using the formula:
Volume = (4/3)π × radius³

3. Use the water displacement method to find the volume of an object if the water level in a graduated cylinder rises from 60 ml to 85 ml after submerging the object.

Conclusion

Knowing how to measure volume is a fundamental skill in science. It allows you to accurately measure space, which is essential for many practical applications and theoretical explorations. By mastering these techniques and understanding the principles behind them, students gain a better understanding of the physical world around them.


Grade 7 → 2.6


U
username
0%
completed in Grade 7

← Prev (2.5)
Measuring time with accuracy
Next (2.7) →
Measuring Temperature and Temperature Scales

Comments 



Measuring the Volume of Regular and Irregular Objects

https://www.physicsflow.com/g7/2.6?pfal=en