Everyday Physics

Understanding the physics behind everyday phenomena and common questions

Subcategories

Electromagnetic Phenomena

Understanding everyday electromagnetic phenomena and electrical effects

Mechanical Phenomena

Understanding everyday mechanical phenomena and why objects behave as they do

Optical Phenomena

Understanding everyday optical phenomena and why we see what we see

Thermal Phenomena

Understanding everyday thermal phenomena and heat-related effects

Topics

A lever works by using a rigid bar that pivots on a fulcrum. Applying force at one point creates a larger force at another point, allowing you to lift heavy objects with less effort. The mechanical advantage depends on the distances from the fulcrum to the force and load.

How does a pendulum work?

A pendulum works by converting between potential and kinetic energy as it swings. Gravity pulls the pendulum downward, and inertia carries it past the bottom, creating oscillating motion. The period (swing time) depends on length and gravity, not mass or amplitude.

Why do objects fall at the same rate?

Objects fall at the same rate (in vacuum) because gravity accelerates all objects equally, regardless of mass. Heavier objects have more gravitational force, but they also have more mass, so the acceleration (force divided by mass) is the same for all objects.

Why do we feel weightless in space?

We feel weightless in space because we're in free fall—orbiting objects are constantly falling toward Earth, but their forward motion keeps them in orbit. Since everything falls together, there's no force pushing against us, creating the sensation of weightlessness.

Why do we have friction?

We have friction because surfaces are not perfectly smooth—microscopic bumps and irregularities interlock and resist motion. Friction helps us walk, grip objects, and control motion, making it essential for many everyday activities.

How do mirrors create reflections?

Mirrors create reflections by having smooth, polished surfaces that bounce light back. When light hits a mirror, it reflects at the same angle it arrived (angle of incidence equals angle of reflection), creating clear, organized reflections that form images.

How do sunglasses work?

Sunglasses work by reducing the amount of light reaching your eyes through tinting (absorbing light) and often polarization (filtering specific light orientations). They protect eyes from bright light, reduce glare, and block harmful UV radiation.

Why do shadows form?

Shadows form because light travels in straight lines and cannot pass through opaque objects. When an object blocks light, it creates a dark region (shadow) where light cannot reach. The shadow's size and shape depend on the light source and object position.

Why do we see colors in soap bubbles?

We see colors in soap bubbles because of thin-film interference. Light reflects from both the front and back surfaces of the bubble film, and these reflections interfere. Different wavelengths interfere constructively or destructively at different film thicknesses, creating the colorful patterns we see.

Why do we see mirages?

We see mirages because hot air near the ground has different density than cooler air above, causing light to refract (bend). This creates the illusion of water or objects appearing where they don't exist, with the image often appearing inverted or distorted.

How does a refrigerator work?

A refrigerator works by using a refrigerant that evaporates inside (absorbing heat and cooling) and condenses outside (releasing heat). A compressor circulates the refrigerant, and the cycle continuously removes heat from inside the refrigerator, keeping it cold.

How does a thermometer work?

A thermometer works by using a substance that expands or contracts with temperature changes. Liquid thermometers use mercury or alcohol that expands in a narrow tube, with the height indicating temperature. Digital thermometers use temperature-sensitive electrical properties.

Why do we feel cold when wet?

We feel cold when wet because water evaporates from our skin, and evaporation requires energy (latent heat of vaporization). This energy comes from our body heat, cooling our skin and making us feel cold.

Why does metal expand when heated?

Metal expands when heated because increased temperature makes atoms vibrate more, increasing the average distance between atoms. This thermal expansion occurs in all materials but is more noticeable in metals due to their rigid structure and common use in construction.

Why does wind feel cold?

Wind feels cold because it increases heat loss from your body through convection and evaporation. Moving air removes the warm air layer around your skin and increases evaporation of moisture, both of which cool your body faster than still air.