Physics
Form 4 · 30 topics available
Chapter 1 · Measurement
Chapter 2 · Force and Motion I
Linear Motion
Linear motion is movement along a straight line, described using displacement, velocity and acceleration and the equations of motion.
OpenMotion Graph
Motion graphs show how displacement or velocity changes with time; their gradients and areas reveal velocity, acceleration and distance.
OpenFree Falling
A freely falling object moves under gravity alone, accelerating downward at g ≈ 9.81 m s⁻² regardless of its mass.
OpenInertia
Inertia is the tendency of an object to resist any change to its state of rest or uniform motion, and it increases with mass.
OpenMomentum
Momentum is the product of an object's mass and velocity, and total momentum is conserved in a closed system.
OpenEffect of a Force
A resultant force can change an object's speed, direction or shape, and Newton's second law links force, mass and acceleration.
OpenImpulse and Impulsive Force
Impulse is the change in momentum, and impulsive force is the large force acting over the short time of an impact.
OpenWeight
Weight is the gravitational force on an object's mass, calculated as W = mg and measured in newtons.
OpenChapter 3 · Gravitation
Newton's Universal Law of Gravitation
Every mass in the universe attracts every other mass with a force that grows with the masses and weakens with the square of their separation.
OpenKepler's Laws
Kepler's three laws describe the shapes, speeds and periods of planetary orbits, and follow directly from Newton's law of gravitation.
OpenMan-made Satellites
A man-made satellite stays in orbit when gravity provides exactly the centripetal force needed for its circular motion around the Earth.
OpenChapter 4 · Heat
Thermal Equilibrium
When two objects in contact reach the same temperature, there is no net heat flow between them and they are said to be in thermal equilibrium.
OpenSpecific Heat Capacity
Specific heat capacity is the heat needed to raise the temperature of 1 kg of a substance by 1 °C, and it explains why some materials heat up faster than others.
OpenSpecific Latent Heat
Specific latent heat is the heat needed to change the state of 1 kg of a substance without any change in temperature.
OpenGas Laws
The gas laws relate the pressure, volume and temperature of a fixed mass of gas, showing how changing one quantity affects the others.
OpenChapter 5 · Waves
Fundamentals of Waves
A wave carries energy and information from one place to another without transferring the medium itself.
OpenDamping and Resonance
Damping gradually reduces the amplitude of an oscillation, while resonance makes it grow when the driving frequency matches the natural frequency.
OpenReflection of Waves
When a wave hits a barrier it bounces back so that the angle of reflection equals the angle of incidence, with speed, frequency and wavelength unchanged.
OpenRefraction of Waves
Refraction is the change in direction of a wave when its speed changes on passing from one medium (or depth) to another, while its frequency stays constant.
OpenDiffraction of Waves
Diffraction is the spreading of waves as they pass through a gap or around an obstacle, and is most pronounced when the gap is about the size of the wavelength.
OpenInterference of Waves
Interference occurs when two coherent waves overlap and superpose, reinforcing each other at some points and cancelling at others.
OpenElectromagnetic Waves
Electromagnetic waves are transverse waves that carry energy through a vacuum at the speed of light and form a spectrum from radio waves to gamma rays.
OpenChapter 6 · Light and Optics
Refraction of Light
Refraction is the bending of light as it passes from one medium into another because its speed changes.
OpenTotal Internal Reflection
Total internal reflection occurs when light in a denser medium strikes a boundary beyond the critical angle and is completely reflected back.
OpenImage Formation by Lenses
Convex and concave lenses form images by refracting light, and ray diagrams predict the position, size and nature of the image.
OpenThin Lens Formula
The thin lens formula 1/f = 1/u + 1/v links focal length, object distance and image distance so image positions can be calculated.
OpenOptical Instruments
Optical instruments such as the magnifying glass, microscope and telescope combine lenses to enlarge or bring closer the images we see.
OpenImage Formation by Spherical Mirrors
Concave and convex mirrors reflect light to form images whose position and nature depend on where the object is placed.
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