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GRADE 10 PHYSICS EXAM NOTES
Very detailed Grade 10 physics revision notes in a sample-style layout.
1. INTRODUCTION TO PHYSICS AND MEASUREMENT
Physics is the study of matter, energy, motion and the forces that act on objects. It explains how the world works from very small particles to large structures like planets and stars. Measurements must be accurate and consistent because physics depends on numbers, units and evidence. A unit tells us what kind of measurement is being used. Without standard units, it would be impossible to compare results from different places. Scientists use the SI system to keep measurements uniform.
l Length: metre (m)
l Mass: kilogram (kg)
l Time: second (s)
l Temperature: kelvin (K) or degree Celsius (°C)
l Force: newton (N)
2. DISTANCE, DISPLACEMENT, SPEED AND VELOCITY
Distance is the total path travelled, while displacement is the straight-line change in position with direction. Speed tells how quickly distance is covered, but velocity is speed in a particular direction. This difference is important when solving motion questions. When an object moves, its motion can be represented in words, by calculations or with graphs. Graphs make it easier to see changes in motion over time.
l Uniform motion: equal distances in equal times.
l Non-uniform motion: changing speed or direction.
l Gradient of a distance-time graph gives speed.
l Gradient of a velocity-time graph gives acceleration.
Formula / key equation: Speed = Distance ÷ Time
3. ACCELERATION, FORCE AND NEWTON'S IDEAS
Acceleration is the rate of change of velocity. An object accelerates when its speed changes, its direction changes, or both. Forces cause acceleration, so a balanced force does not change motion while an unbalanced force does. Newton’s ideas help explain everyday situations such as walking, driving, stopping and falling. Inertia means an object resists changes to its motion.
l Force is a push or pull.
l Mass measures the amount of matter in an object.
l Weight is the force of gravity on a mass.
l Friction and air resistance oppose motion.
Formula / key equation: Force = Mass × Acceleration
4. DENSITY, PRESSURE AND UPTHRUST
Density is a useful idea when comparing materials. It tells us how much mass is packed into a given volume. High-density materials contain more mass in the same space than low-density materials. Pressure is force spread over an area. These concepts explain floating, sinking, sharp objects, tyres, dams and hydraulic systems. A smaller contact area produces a greater pressure for the same force.
l Water has a fixed density at a given temperature.
l Objects float when their average density is lower than the fluid.
l Upthrust is the upward force exerted by a fluid.
l Pressure increases with depth in a fluid.
Formula / key equation: Density = Mass ÷ Volume ; Pressure = Force ÷ Area
5. WORK, ENERGY, POWER AND EFFICIENCY Work is done when a force moves an object through a distance. Energy is the ability to do work. Different energy forms can change into one another, but the total energy is conserved. This is one of the most important rules in physics. Power describes how fast work is done or energy is transferred. Efficiency tells us how much useful energy is obtained from the total input energy.
l Kinetic energy: energy of motion.
l Potential energy: stored energy due to position or condition.
l Thermal energy: energy associated with temperature.
l No machine is perfectly efficient because some energy is always wasted.
Formula / key equation: Work done = Force × Distance ; Power = Work ÷ Time
6. HEAT, THERMAL EXPANSION AND TRANSFER OF ENERGY Heat is energy transferred from a hotter object to a cooler one. Temperature measures how hot something is. Heating usually causes expansion because particles move more and take up more space. Cooling causes contraction. Heat can move in three ways: conduction, convection and radiation.
l Conduction: transfer through direct contact, mainly in solids.
l Convection: transfer by movement in fluids.
l Radiation: transfer by electromagnetic waves, and it can travel through vacuum.
l Shiny surfaces reflect heat well; dull dark surfaces absorb and emit heat well.
7. WAVES, SOUND AND LIGHT A wave is a disturbance that transfers energy from place to place. Waves can be transverse or longitudinal. Sound is a longitudinal wave and needs a medium. Light is an electromagnetic wave and can travel through space. Wave properties include amplitude, wavelength, frequency, period and speed. These terms are often tested in calculations and graph interpretation.
l Amplitude is the maximum displacement from the rest position.
l Wavelength is the distance between matching points on consecutive waves.
l Frequency is the number of waves per second.
l Higher amplitude usually means louder sound.
l Higher frequency means higher pitch.
8. REFLECTION, REFRACTION AND LENSES Reflection happens when light bounces off a surface. The angle of incidence equals the angle of reflection. Refraction happens when light changes speed as it moves from one medium to another, causing it to bend. Lenses are used to focus light. Convex lenses converge light rays, while concave lenses diverge them. These principles are used in eyes, cameras, microscopes and spectacles.
l Normal = line at right angles to the reflecting surface.
