Classical Mechanics
Understanding motion, forces, and the fundamental laws that govern how objects move
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How does centripetal force work?
Centripetal force is the force that keeps an object moving in a circular path, always pointing toward the center of the circle. It doesn't create the motion but changes the direction of velocity, causing the object to curve instead of moving in a straight line.
Read more →How does conservation of momentum work?
Conservation of momentum states that the total momentum of a closed system remains constant unless acted upon by external forces. When objects collide or interact, their individual momenta may change, but the total momentum before and after the interaction remains the same.
Read more →How does Newton's first law work?
Newton's first law states that an object at rest stays at rest, and an object in motion continues moving at constant velocity unless acted upon by an unbalanced force. This describes the property of inertia.
Read more →How does Newton's second law work?
Newton's second law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. This is expressed as F = ma (force equals mass times acceleration).
Read more →How does Newton's third law work?
Newton's third law states that for every action, there is an equal and opposite reaction. When object A exerts a force on object B, object B simultaneously exerts an equal and opposite force on object A.
Read more →What is angular momentum?
Angular momentum is a measure of how much rotational motion an object has, calculated as the product of its moment of inertia (rotational mass) and angular velocity (rotational speed). Like linear momentum, angular momentum is conserved unless acted upon by an external torque.
Read more →What is momentum?
Momentum is the quantity of motion an object has, calculated by multiplying its mass by its velocity. It describes how difficult it is to stop a moving object and is conserved in collisions.
Read more →What is torque?
Torque is a measure of how much a force causes an object to rotate around an axis. It's calculated as force multiplied by the distance from the axis of rotation (lever arm), and it determines how effectively a force can cause rotational acceleration.
Read more →Why do spinning objects stay upright?
Spinning objects stay upright due to conservation of angular momentum and gyroscopic stability. The spinning motion creates angular momentum that resists changes in orientation, making the object stable and able to maintain its upright position even when disturbed.
Read more →Why do we have friction?
Friction exists because surfaces are not perfectly smooth—microscopic bumps and irregularities on surfaces interlock and resist motion. Friction helps us walk, grip objects, and control motion.
Read more →How do satellites stay in orbit?
Satellites stay in orbit by balancing two factors: their forward velocity and Earth's gravitational pull. They move fast enough horizontally that as they fall toward Earth due to gravity, Earth's curved surface curves away beneath them, creating a stable circular or elliptical path.
Read more →How does gravity affect objects?
Gravity affects objects by pulling them toward each other with a force proportional to their masses and inversely proportional to the square of the distance between them. This causes objects to accelerate, fall, and orbit.
Read more →How does gravity affect time?
Gravity affects time through time dilation, a prediction of Einstein's general theory of relativity. Time runs slower in stronger gravitational fields—clocks tick slower near massive objects like Earth compared to clocks in weaker gravitational fields or far from massive objects.
Read more →How does the moon affect tides?
The Moon affects tides through its gravitational pull on Earth's oceans. The Moon's gravity is stronger on the side of Earth facing the Moon, pulling water toward it and creating high tides. The Sun also contributes to tides.
Read more →What is escape velocity?
Escape velocity is the minimum speed an object needs to escape a planet's or moon's gravitational pull without further propulsion. For Earth, escape velocity is approximately 11.2 kilometers per second.
Read more →What is gravitational potential energy?
Gravitational potential energy is the energy an object possesses due to its position in a gravitational field. It represents the work that gravity can do on the object as it moves to a reference point, typically calculated as mgh (mass × gravitational acceleration × height) near Earth's surface.
Read more →What is the difference between mass and weight?
Mass is the amount of matter in an object (a constant property), while weight is the force of gravity acting on that mass (which varies with location). Mass is measured in kilograms and doesn't change, while weight is measured in newtons and changes with gravitational strength.
Read more →Why do comets have elliptical orbits?
Comets have elliptical orbits because they don't have enough velocity for circular orbits when they're far from the sun. Their orbits are highly elliptical due to conservation of energy and angular momentum—they move slowly when far from the sun and faster when close, following Kepler's laws of planetary motion.
Read more →Why do planets orbit the sun?
Planets orbit the Sun because the Sun's gravity pulls them inward while their forward motion carries them forward. These two forces balance, creating a stable elliptical orbit instead of planets falling into or flying away from the Sun.
Read more →Why is gravity weaker on the moon?
Gravity is weaker on the Moon because the Moon has less mass than Earth. Since gravitational force depends on mass, the Moon's smaller mass creates a gravitational field about one-sixth as strong as Earth's.
Read more →How do projectiles move?
Projectiles move in curved paths called parabolas due to the combination of horizontal motion (constant velocity) and vertical motion (constant acceleration downward due to gravity). The horizontal and vertical motions are independent, creating the characteristic curved trajectory.
Read more →How does gravity work?
Gravity is a fundamental force that attracts all objects with mass toward each other. The strength of gravity depends on the mass of the objects and the distance between them, following Newton's law of universal gravitation.
Read more →What is acceleration?
Acceleration is the rate at which an object's velocity changes over time. It describes how quickly an object speeds up, slows down, or changes direction.
Read more →What is displacement?
Displacement is the change in position of an object from its starting point to its ending point, measured in a straight line with direction. Unlike distance, displacement is a vector quantity that includes both magnitude and direction.
Read more →What is free fall?
Free fall is the motion of an object falling under the influence of gravity alone, with no other forces (like air resistance) acting on it. In free fall, all objects accelerate downward at the same rate, approximately 9.8 m/s² on Earth, regardless of their mass.
Read more →What is the difference between speed and velocity?
Speed is how fast an object is moving (a scalar quantity with only magnitude), while velocity is how fast an object is moving in a specific direction (a vector quantity with both magnitude and direction). The key difference is that velocity includes direction, while speed does not.
Read more →What is velocity?
Velocity is the rate at which an object changes its position, including both speed and direction. Unlike speed, velocity is a vector quantity that describes how fast something is moving and in which direction.
Read more →Why do objects fall?
Objects fall due to gravity, a fundamental force that pulls all objects with mass toward each other. On Earth, gravity pulls objects toward the center of the planet, causing them to fall downward.
Read more →Why do objects follow curved paths?
Objects follow curved paths when forces act perpendicular to their direction of motion, changing their direction continuously. Common causes include gravity (creating parabolic paths for projectiles), centripetal forces (creating circular paths), and the combination of multiple forces acting at angles to the motion.
Read more →Why do objects move?
Objects move because of forces acting on them. According to Newton's laws of motion, an object at rest stays at rest unless acted upon by a force, and an object in motion continues moving unless acted upon by a force.
Read more →How do sound waves travel?
Sound waves travel by creating compressions and rarefactions in a medium like air, water, or solid materials. These pressure variations propagate outward from the source, transferring energy as they move.
Read more →How do standing waves form?
Standing waves form when two waves of the same frequency and amplitude travel in opposite directions and interfere with each other. The interference creates fixed points called nodes (no motion) and antinodes (maximum motion), creating a wave pattern that appears to stand still rather than travel.
Read more →How does an echo work?
An echo works through sound wave reflection. When sound waves hit a hard surface, they bounce back toward the source. If the reflected sound reaches your ears more than about 0.1 seconds after the original sound, your brain perceives it as a separate echo rather than part of the original sound.
Read more →How does resonance work?
Resonance occurs when an object is forced to vibrate at its natural frequency, causing it to oscillate with maximum amplitude. This happens when the frequency of an applied force matches the object's natural frequency.
Read more →What is a wave?
A wave is a disturbance that travels through space or matter, transferring energy without transferring matter itself. Waves can be mechanical (like sound or water waves) or electromagnetic (like light), and they all share common properties like wavelength, frequency, and amplitude.
Read more →What is amplitude?
Amplitude is the maximum displacement of a wave from its equilibrium position. For sound waves, amplitude determines volume (loudness), and for light waves, it determines brightness.
Read more →What is frequency?
Frequency is the number of complete wave cycles that pass a given point per second. It's measured in hertz (Hz) and determines the pitch of sound waves and the color of light waves.
Read more →What is the Doppler effect?
The Doppler effect is the change in frequency and wavelength of a wave observed when the source of the wave or the observer is moving relative to each other. When approaching, waves are compressed (higher frequency), and when receding, waves are stretched (lower frequency).
Read more →What is wavelength?
Wavelength is the distance between two consecutive points in a wave that are in the same phase, such as from one crest to the next crest or from one trough to the next trough. It's typically measured in meters and determines many wave properties including frequency and energy.
Read more →Why do some sounds travel faster than others?
Sound speed depends on the properties of the medium it travels through, not the sound itself. Sound travels faster in denser, stiffer materials—faster in solids than liquids, faster in liquids than gases. Temperature also affects speed in gases, with sound traveling faster in warmer air.
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