Physics for Beginners

Describe how things move using words and math through kinematics, and apply these ideas to basketballs in flight and objects moving along a road.

Learn how physicists use subscripts for initial and final values and delta for change, forming combined quantities like delta v and delta x to compare velocity and position.

Explore vectors, their magnitude and direction, and master the tip-to-tail method to add velocity or position vectors. View subtraction as adding the negative vector and get the resultant.

Explore displacement, the vector describing the change in an object's position from start to end. Learn how displacement differs from distance and equals the straight-line path between points.

Explore distance and displacement on a rectangular track, showing three laps yield 900 m distance and 0 m displacement, while a half-loop yields 150 m distance and 50 m displacement.

Discover velocity as the rate of change of displacement over time and its directional nature. Compare velocity with speed, noting that velocity is a vector with positive or negative direction.

Discover acceleration as the rate of change of velocity over time, and understand how velocity has direction and relates to displacement.

the lecture clarifies average versus instantaneous velocity, showing a bar denotes average and the slope of a position-time graph gives instantaneous velocity, with displacement over time defining velocity and jerk.

Explore relative motion through reference frames, showing how speeds of car A and car B appear differently to observers. Apply the relative velocity formula with mph examples.

Explore today’s kinematics by analyzing what equations and graphs mean, focusing on 1D and 2D kinematics and the idea of dimensions and the separation of directions.

Analyze one-dimensional kinematics by examining constant velocity, constant acceleration, and changing acceleration, using time-segment reasoning and the relationship between velocity and position via velocity-time and position-time graphs.

Explore constant acceleration with velocity-time graphs, using slope and area under the curve to find displacement; example shows starting from rest reaching 8 m/s in 5 s, covering 20 m.

Explore kinematic equations for acceleration, linking final velocity, initial velocity, time, and displacement. Learn to pick the right equation using givens and unknowns, with three quantities solving for a fourth.

Explore free fall as constant gravity acceleration, with feather and bowling ball demonstrations showing air resistance; contrast Earth and Moon gravity, noting one-sixth gravity on the Moon and weight changes.

Solve a free fall question using a velocity-time graph for g ≈ 10 m/s², starting from rest, equate area under the curve to 10 meters, yielding t = sqrt(2) s.

Explore how force, though not a thing, changes motion and is measured in Newtons; learn that forces are vectors, depicted by arrows, arising from interactions, leading to Newton's laws.

Explore the forces acting on Fred, including gravity, the normal force, atmospheric pressure, wind, and friction on a slope, and learn how to simplify diagrams.

Explore Newton's first law, or inertia, which says objects stay at rest or in motion unless a net force acts. Equal opposing forces yield zero net force and no motion.

Explore Newton's second law, f equals ma, showing how a net force causes acceleration and how mass resists this change, illustrating inertia with simple everyday examples.

Explore Newton's third law, the action and reaction pair, and how rockets propel by expelling propellants as momentum is conserved, with examples from walking, cars, planes, and space.

Explore contact and non-contact forces, including friction, tension, normal force, spring force, air friction, gravity, electric force, and magnetic force.

Explore the four fundamental forces—gravity, the electromagnetic force, the strong force, and the weak force—and how they underlie all other forces, from friction to nuclear binding.

Explore gravitational force as an attractive interaction between masses. Learn how its strength depends on mass and distance, and how Newton's third law yields equal and opposite forces.

Explore normal force, the contact force that prevents objects from passing through each other and counters gravity. Examine friction, a contact force that resists motion, with static and kinetic types.

Explore the elastic force, a category of forces that resist shape change, including tension, compression, torsion, and spring force, with Hooke's law as the underlying math.

Learn to draw a free body diagram for a block on a ramp, showing gravity, normal force, and friction, with vectors directed and sized to balance the incline.

Review previous material and explore friction force, its calculation, and how weight, normal forces, and tension relate to scale readings and Newton's second law–driven acceleration.

Learn how net force causes acceleration by combining forces in opposite directions, analyze unbalanced versus balanced force scenarios, and explore a tug-of-war simulation.

Analyze how balanced forces produce no acceleration while unbalanced forces cause acceleration, and determine the net force's magnitude and direction for a box using left-right references.

Discover static and kinetic friction, how normal force and the coefficient of friction determine the resisting force, and why surface roughness and weight affect motion.

Learn how the coefficient of friction, symbol mu, relates roughness and normal force to static and kinetic friction, including maximum static friction and its inequality.

Analyze how elevator acceleration alters scale readings by comparing weight and the normal force. Apply free-body diagrams and Newton's second law to reveal apparent weight and weightlessness.

Explore work and energy, examine different energy types, and learn the conservation of energy, then relate work to energy and practice conservation of energy problems.

Explore energy as a quantity that describes and drives motion within a chosen system, where internal and external objects are distinguished, and energy conservation guides problem solving, measured in joules.

Explore kinetic and potential energy and their everyday examples, including chemical, gravitational, electrical, elastic, thermal, sound, light, and nuclear energy, with real-world applications.

Learn how energy is conserved, cannot be created or destroyed, and simply transfers between forms like chemical and kinetic energy, a math quantity that enables calculations across everyday processes.

Explore kinetic energy, its dependence on mass and speed, and why energy is a scalar despite velocity being a vector. The lecture also covers negative mass, gravity, and energy concepts.

Explore gravitational potential energy using the m g h formula, learn how choosing a zero height affects energy comparisons, and recognize its limitations for large distances.

See how forces transfer energy through work, converting muscle energy to kinetic energy and gravity's potential energy to kinetic energy, while work equals change in energy and can be negative.

Apply conservation of energy by equating initial and final kinetic and potential energies, then solve for the speed. For example, a ball's speed before impact is about 14.1 m/s.

Explore momentum and its relation to force, and introduce the momentum conservation law. Examine internal versus external forces, collisions and their types, and the center of mass.

Compute momentum as mass times velocity, a vector with magnitude, direction, and units (kilograms × meters per second), using a sample block moving to the right.

Explore momentum change under force using delta p = F delta t and the rate form, F = dp/dt, and relate p = m v to F delta t = m delta v.

Explore how momentum is conserved in closed systems, how momentum transfers between objects like rolling balls, and how external forces can affect conservation.

Identify internal forces between objects inside a chosen system and external forces from outside, including Newton's third law pairs, using gravity and collisions to illustrate momentum and energy conservation.

Analyze momentum conservation in collisions, where two objects exchange velocities under internal forces, and distinguish elastic, inelastic, and perfectly inelastic collisions with possible kinetic energy loss.

Use conservation of momentum on a frictionless two-block collision to solve for the red block’s final velocity, given masses, initial speeds, and possible perfectly inelastic outcomes.

Use conservation of momentum in a perfectly inelastic collision, 1 kg and 10 kg boxes moving at 3 m/s and -2 m/s stick and move at 1.55 m/s left.

Explore the center of mass, or center of gravity, the balance point of an object as the average mass position. See how density and shape affect it.

Explore gravity from multiple viewpoints, blending historical and mathematical ideas with conceptual understanding, compare free fall in air and vacuum, and touch on orbital motion and solar system gravity.

Explore Newton's law of universal gravitation, describing gravity as an attractive force between two masses, scaling with their distance squared.

Explore a PHET simulation to understand how mass and distance affect gravity, showing that doubling mass doubles the force and doubling distance reduces the force by four.

Trace the history of gravity from Isaac Newton's description and the Apple story to Albert Einstein's theory of relativity, which describes gravity as bending space time.

Explore gravitational potential energy beyond the m g h formula, revealing a 1/r energy relation with a negative sign and showing that increasing distance raises potential energy, illustrated through graphs.

Explore how gravity governs circular motion and orbital paths of planets and the moon, using a simulation that shows how mass and velocity shape orbits.

Explore electrostatics by examining electric charge and real-world demonstrations you can do, showing how these phenomena appear in daily life and simple experiments.

Explore electrostatics, the branch of electromagnetism that studies stationary charges or charges moving very slowly, distinguishing it from dynamics.

Understand electric charge as a property of elementary particles that enables the electromagnetic force of attraction and repulsion. Learn about protons, electrons, neutrons, and the coulomb.

Explore how electric forces cause charges to repel when signs match and attract when signs differ. Understand charge conservation and how small charge differences yield strong forces compared with gravity.

Learn how conductors let electrons move freely, while insulators hold them in place, with metals as good conductors and rocks or rubber as insulators.

Learn how friction charges objects by transferring electrons based on electron affinity, creating positive and negative charges. See conduction and induction with touching and distant rods to illustrate charge redistribution.

Bringing a charged object near a neutral object rearranges charges, producing attraction via polarization. A negatively charged balloon near a wall makes the near side positive, letting it stick.

Coulomb's law describes the electric force between charges, using a gravity-like formula with charge Q and distance. Use k, not g, and see attraction or repulsion via charge sign.

Explore electrostatics with a Phet simulation to visualize electric fields from charges, dipoles, field strength versus distance, and how test charges move and where zero-field points occur.

Define circuits, identify their parts, and highlight the key quantities and measurements used in circuit analysis. Explore how circuits are created and apply the governing law to solve specific problems.

Explore how a circuit passes electricity to power light bulbs and appliances, and how it sends signals in computer chips by changing voltages, currents, and parts of a circuit.

Explore how current, resistance, and voltage govern circuits, with current as the flow of charges measured in amperes, resistance in ohms, and voltage as energy per charge.

Explore circuit components, including batteries, power supplies, wires, and switches, and see how voltage drives current. Learn how resistors provide resistance and convert electrical energy into heat to control circuits.

Discover how light bulbs convert electrical energy to light, comparing incandescent bulbs that heat a filament to glow with leds that use a different principle and offer greater energy efficiency.

Master circuit diagram symbols, including wires, resistors, inductors, light bulbs, batteries, fuses, circuit breakers, and switches, and learn how orientation and safety features protect circuits.

Explore how resistors connect in series and parallel to control total resistance, and apply the reciprocal formula to nested circuits.

Explore Ohm's law, linking voltage, current, and resistance with V = I R, and see its similarity to f = ma while solving simple circuits.

Power is the rate of electrical energy used or transferred over time. It is calculated as current squared times resistance, P equals I squared R, with watts as the unit.

Explore a circuit simulation with a battery, wires, and resistors to see how changing resistance and adding branches affects current and brightness, using voltage and ammeters.