The image above is actually about internet of things. Well, things follows the laws of physics ...
Physics is all around us. From the air we breathe, to the light that lets us see, to the gadgets we use, and even to our own bodies -- everything in our daily lives is governed by the laws of physics. Yet, we rarely stop to think about the invisible forces and principles at work every second of the day. Understanding the physics behind everyday phenomena not only satisfies curiosity but also deepens our appreciation for the world we live in.
In this article, we explore some of the key areas where physics manifests itself in the world around us. We'll cover the principles of motion, forces, energy, waves, light, sound, electricity, heat, and much more -- all in the context of things you encounter in your daily life.
Motion and Forces in Everyday Life
Whenever you move -- walking, running, driving a car -- you are engaging with Newton's laws of motion.
Walking and Running
When you walk, you push backward on the ground with your foot. According to Newton's third law, the ground pushes you forward with an equal and opposite force. If the ground were slippery (like ice), you wouldn't be able to push effectively, and walking would be much harder. This is why traction -- friction between your shoes and the ground -- is essential.
When running, you accelerate. According to Newton's second law, the harder you push against the ground, the greater the force, and the more your velocity increases.
Cars and Bicycles
Driving a car or riding a bicycle involves balancing forces. The engine or your pedaling provides a force that propels you forward. But air resistance (drag) and friction in the tires oppose your motion. If you stop applying force, friction and drag eventually bring you to a stop.
Braking applies a force in the opposite direction of motion, decelerating you. The tires' friction on the road converts your car's kinetic energy into heat, which is why brakes can become very hot.
Energy in Daily Activities
Energy makes everything happen. The food you eat is chemical energy, which your body converts into kinetic energy (motion), thermal energy (heat), and even electrical energy (for nerve impulses).
Clocks and Watches
Mechanical clocks use stored potential energy (in a wound spring or raised weight) that gradually turns into kinetic energy to keep the hands moving. Battery-powered watches rely on chemical energy stored in the battery, converted into electrical energy to power the electronics.
Appliances and Electricity
Your household appliances -- like your refrigerator, television, or laptop -- convert electrical energy from the power grid into forms you can use: light, sound, or motion.
Waves: Sound and Water
Many phenomena we encounter daily are wave-based. Sound, water ripples, and even light are examples of waves.
Sound
When you speak, your vocal cords vibrate, producing sound waves -- oscillations of air molecules that travel through the air to someone else's ears. The pitch of your voice corresponds to the frequency of these vibrations: high frequency for high notes, and low frequency for deep notes.
Sound waves also bounce off surfaces, causing echoes. In some rooms, sound waves interfere constructively and destructively, creating "dead spots" or loud zones -- something architects consider when designing concert halls.
Water Waves
When you throw a stone into a pond, you see ripples spreading out. These are surface waves: oscillations of water molecules moving up and down while the energy travels outward. Surfers take advantage of the energy carried by ocean waves, which come from wind transferring energy to the sea's surface.
Light and Vision
How We See
Light enters your eyes and is focused by the lens onto your retina, where it's converted into electrical signals for your brain to interpret. The bending of light by your eye's lens is refraction, governed by Snell's law.
When you wear glasses, they correct the path of light so it focuses correctly on your retina. Nearsighted people need lenses that diverge light slightly; farsighted people need lenses that converge it more.
Colors
Why is the sky blue? Sunlight contains all colors of light. The atmosphere scatters shorter (blue) wavelengths more effectively than longer (red) ones, so we see a blue sky. At sunset, sunlight passes through more atmosphere, scattering away blue light and leaving reds and oranges.
Objects appear colored because they reflect certain wavelengths of light and absorb others. A red apple reflects red wavelengths and absorbs the rest.
Heat and Temperature
Heat is another form of energy transfer. When you touch a hot stove, thermal energy flows into your hand because of the temperature difference.
Cooking
When you cook food, you're transferring heat to it. Heat can travel through conduction (pan to food), convection (hot air circulating in an oven), or radiation (microwave ovens use electromagnetic waves to excite water molecules in food).
Weather and Climate
Weather is driven by heat from the sun. The uneven heating of Earth's surface causes air to move -- warm air rises and cooler air rushes in to replace it, creating wind.
Electricity and Magnetism
Most modern conveniences rely on electricity, which is the flow of electric charges.
Powering Homes
Electricity is generated by converting mechanical energy (from turbines powered by steam, water, or wind) into electrical energy using electromagnetic induction -- a discovery by Michael Faraday.
When you flip on a light switch, you complete an electric circuit, allowing electrons to flow through the bulb and produce light.
Magnets and Motors
Magnets produce invisible fields that exert forces on materials like iron. Electric motors use magnets and coils of wire to convert electrical energy into motion -- this is how fans, washing machines, and even your car's starter motor work.
Gravity at Work
Gravity is one of the most familiar forces. It keeps your feet on the ground, governs the motion of planets, and explains why objects fall when dropped.
Falling Objects
When you drop your keys, they accelerate toward the ground due to Earth's gravity, at about 9.8 m/s2. Air resistance can slow down falling objects, which is why a feather and a rock fall at different rates in air but would fall at the same rate in a vacuum.
Tides
The ocean tides are caused by the gravitational pull of the Moon (and to a lesser extent, the Sun) on Earth's water. This is why we have high and low tides that follow a regular pattern.
Pressure in Fluids
Air and water exert pressure. You might not notice atmospheric pressure, but it's about 101,325 pascals at sea level. This is nearly the weight of 10000 kg for every square meter of your body area -- enough to crush you if not for the equal pressure inside your body pushing back. An adult African elephant is about 5000 kilograms
Breathing
When you inhale, you expand your lungs, reducing the air pressure inside them. Air flows in because the external atmospheric pressure is higher. When you exhale, the process reverses.
Water and Buoyancy
When you swim, you feel lighter. That's because water exerts an upward buoyant force equal to the weight of the water you displace. This is Archimedes' principle, and it's why ships float despite being made of heavy steel -- they displace a large volume of water.
Modern Technology and Physics
Many technologies you use daily rely on advanced physics principles.
Smartphones
Your phone's touchscreen uses the physics of capacitance -- changes in the electric field when your finger (which conducts electricity slightly) touches the screen. Its display relies on liquid crystals or organic LEDs, which emit light when electric current passes through them.
GPS works by using signals from satellites and calculating your position based on the time it takes for signals to reach you -- accounting for relativity because the satellites are moving fast and are farther from Earth's gravity.
Internet and Communication
Fiber-optic cables carry light signals over long distances using total internal reflection, a phenomenon where light stays trapped inside the glass fiber. Wireless signals use electromagnetic waves to send information through the air.
Sports and Physics
Every sport is governed by physics.
Baseball and Soccer
In baseball, hitting a home run requires converting energy from your muscles into kinetic energy of the bat and then into the ball. The ball's trajectory is a parabola shaped by gravity and air resistance.
In soccer, the curved path of a spinning ball (a "banana kick") is due to the Magnus effect: the ball's spin creates a pressure difference, causing it to curve.
Swimming and Cycling
Competitive swimmers streamline their bodies to reduce drag. Cyclists wear aerodynamic helmets to minimize air resistance, which increases with the square of velocity.
Everyday Questions Answered by Physics
- Why do we slip on ice? Because the friction between your shoes and ice is very low, so it's hard to generate enough force to stay stable.
- Why does toast always seem to land butter-side down? Not always, but it's partly because of the way it rotates as it falls from typical table height -- it usually completes about half a turn.
- Why do your ears pop in elevators? As you go up or down, air pressure changes, and your eardrum adjusts to equalize pressure inside and outside.
Conclusion: Physics Is Everywhere
From the moment you wake up and turn off your alarm, to the time you lay your head down at night, physics shapes every experience. It explains how light allows you to see, how sound lets you hear, how your car moves, and even why the Earth stays in orbit around the Sun.
Understanding the physics of things around us doesn't just make life more interesting -- it helps us solve problems, improve technologies, and make better decisions in our daily lives.
The next time you turn on a light, sip a hot cup of coffee, or watch a sunset, take a moment to appreciate the incredible physics at play. The universe is full of wonders, and physics is the language that describes them.
You can learn these concepts and more at Dr Hock's maths and physics tuition.