Source: Yale University, Open Yale Courses
First 10 minutes: some comments about assignment "Is the controversy about Pluto a scientific controversy?"; science can be affected by culture. Motion of star and planet around the center of mass. Graph of radial velocities interpreted as a system containing 3 planets. Back to "hot jupiters": discovery of 51 Peg b shows the importance of "expecting the unexpected". Alternative explanations of hot jupiters (double star systems, pulsating stars) proved wrong.
See other lectures in this series.
Saturday, 29 January 2011
MIT 8.01 Classical Mechanics Lecture 4
MIT Physics Course
Professor Walter Lewin
Analysis of the motion of a projectile: time of flight, maximum height, range, experimental verification for angles of 45°, 30° and 60°. From the 35th minute: the well known hunter and monkey problem.
See other videos in this series.
Earthquake (P and S waves)
An earthquake generates a P wave (fast and longitudinal) and a S wave (slower and transversal). Because of its greater velocity, the P wave arrives before the S wave. In this video, the dog senses the P wave 5 seconds before we see the effects of the S wave.
Sunday, 23 January 2011
Rotating Candles in a Dome
A row of candles are placed inside a see-through dome on a rotating platform. When the platform rotates, air inside the dome gets swung to the outer part of the dome, creating higher density air at the outer rim, and lower density air in the middle. The candle flames point inwards towards the middle because the hot gas in the flames always points towards lower density air.
Source: MIT TechTV
See other MIT physics demos
Source: MIT TechTV
See other MIT physics demos
Electric field of a dipole
Electric field lines around a stationary dipole (a pair of electric charges of equal magnitude but opposite sign).
Other animations by Yves Pelletier
Other animations by Yves Pelletier
Saturday, 22 January 2011
Yale: Frontiers and Controversies in Astrophysics, Lecture 4
Source: Yale University, Open Yale Courses
Professor Bailyn talks about formation of planets and why the inner planets (like earth) are different from the outer planets (like jupiter). He calculates the velocity of the sun caused by Jupiter (which is detectable) and the velocity of the sun caused by the earth (which is too small to be detectable). How we use Doppler shift to measure the velocity of distant stars. Data showing an exoplanet orbiting at a short distance from its star, but showing the characteristics of an outer planet: a "hot Jupiter".
See other lectures in this series.
MIT 8.01 Classical Mechanics Lecture 3
MIT Physics Course
Professor Walter Lewin
8.01 Physics I: Classical Mechanics, Fall 1999
This third lecture is mostly about vectors: vector addition, dot product, cross product. In the last 15 minutes: 3-D kinematics: 3-D motion can be described with 3 indenpendant components. Motion of a projectile and, at the 46th minute, experiment showing that horizontal and vertical motion are independant.
See other videos in this series.
See other videos in this series.
Friday, 21 January 2011
Brightstorm: Free-Body Force Diagrams
Some very basic free-body diagrams: book at rest on a table, falling balloon, book in motion on a table.
See other Brighstorm videos
See other Brighstorm videos
Patricia Burchat sheds light on dark matter
Physicist Patricia Burchat sheds light on two basic ingredients of our universe: dark matter and dark energy. Comprising 96% of the universe between them, they can't be directly measured, but their influence is immense.
Other TED Talks
Other TED Talks
Monday, 17 January 2011
Block on inclined plane
A block is held in place on a frictionless inclinend plane by a string. This video shows how the normal force and the tension in the string are affected by the angle of the incline.
Other animations by Yves Pelletier
Other animations by Yves Pelletier
TED Talks: Steven Cowley: Fusion is energy's future
Physicist Steven Cowley is certain that nuclear fusion is the only truly sustainable solution to the fuel crisis. He explains why fusion will work and talks about the projects that he and many others have devoted their lives to, working against the clock to create a new source of energy.
Other TED Talks
Other TED Talks
Sunday, 16 January 2011
Saturday, 15 January 2011
Friday, 14 January 2011
Yale: Frontiers and Controversies in Astrophysics, Lecture 3
Source: Yale University, Open Yale Courses
After some comments about the problem set, professor Bailyn talks about momentum in a star-planet system (from about the sixth minute). 18th minute: our solar system (slide show), trans-Neptunian objects, controversy about Pluto (32nd minute), comets. Astronomy as an observational science, and classification of objects of the solar system in 6 categories.
See other lectures in this series.
Thursday, 13 January 2011
Simple pendulum
Simple pendulum: velocity vector, acceleration vectors (radial acceleration in cyan and tangential acceleration in orange), forces (tension in orange and weight in cyan) and energies (kinetic energy in yellow, gravitational potential energy in green and total mechanical energy in orange).
Other animations by Yves Pelletier
Other animations by Yves Pelletier
Rotating gears
The left gear has 16 teeth and makes 3 revolutions, the center gear has 24 teeth and makes 2 revolutions, the right gear has 12 teeth and makes 4 revolutions.
Other animations by Yves Pelletier
Other animations by Yves Pelletier
Hooke's Law (Brightstorm)
Three simple examples involving Hooke's Law (force exerted by a spring).
See other Brighstorm videos
See other Brighstorm videos
Wednesday, 12 January 2011
Uncompressible Flow and Fluid Velocity
The flow velocity of an uncompressible fluid is determined by the area of the pipe it is flowing through. The more constricted the pipe, the faster the fluid flows (continuity equation).
Other animations by Penn State Schuylkill
Other animations by Penn State Schuylkill
Refraction and reflection of light
When a ray of light reach the boundary between two different substances, some light is reflected, and some light is refracted. The semi-cylindrical piece of glass has a higher index of refraction than air.
Other animations by Yves Pelletier
Other animations by Yves Pelletier
MIT 8.01 Classical Mechanics Lecture 2
MIT Physics Course
Professor Walter Lewin
8.01 Physics I: Classical Mechanics, Fall 1999
Kinematics, straight line motion, average velocity, instantaneous velocity, acceleration, motion with constant acceleration.
At about the 15th minute, professor Lewin measures experimentally the velocity of a bullet. At the end, we observe a free falling object with a stroboscope.
See other videos in this series.
See other videos in this series.
MIT Physics Demo -- Dipole Antenna
An RF transmitter is connected to a long antenna, emitting radio waves. A dipole antenna with a light bulb between its elements acts as the receiver. When the receiving antenna is parallel to the transmitter, the radio waves are absorbed, creating a current in the antenna and causing the bulb to glow. When perpendicular, no current is created, and the bulb does not glow.
See other MIT physics demos
See other MIT physics demos
MIT Physics Demo -- Wooden Block Between Two Strings
A block of wood is attached vertically between two strings. When the bottom string is pulled slowly, the top string breaks. When the bottom string is pulled quickly, it itself breaks.
See other MIT physics demos
See other MIT physics demos
Tuesday, 11 January 2011
Popping a ballon with a laser
95mW green laser pointer popping a red balloon that is inside a clear balloon.
Bell in a bell jar
Sound does not travel in vacuum.
A bell can be heard ringing within a bell jar. The bell jar is connected to a vacuum pump and the air is slowly removed. Once a vacuum has been achieved the pumped is turned off and air is allowed to slowly re-enter the bell jar.
A bell can be heard ringing within a bell jar. The bell jar is connected to a vacuum pump and the air is slowly removed. Once a vacuum has been achieved the pumped is turned off and air is allowed to slowly re-enter the bell jar.
Communicating vessels
The liquid is at the same level in all of the containers regardless of the shape and volume of the containers.
Sunday, 9 January 2011
Conceptual physics: Conservation of Energy
Paul Hewitt demos conservation of kinetic and potential energy with a bowing ball next to his teeth.
Charged particle in a magnetic field
Helicoidal motion of a charged particle in a uniform magnetic field.
Other animations by Yves Pelletier
Other animations by Yves Pelletier
Feather & Hammer Drop on Moon
Here's the famous footage of the Apollo 15 astronaut that dropped a hammer & feather on the moon to prove Galileo's theory that in the absence of atmosphere, objects will fall at the same rate regardless of mass.
Transverse and Longitudinal Waves
This animation depicts Transverse and Longitudinal waves on a spring.
Other animations by Penn State Schuylkill
Other animations by Penn State Schuylkill
Simple harmonic motion
Acceleration vector, graphs of position, velocity and acceleration vs time for a body suspended to a spring.
Other animations by Yves Pelletier
Other animations by Yves Pelletier
Saturday, 8 January 2011
Yale: Frontiers and Controversies in Astrophysics, Lecture 2
Source: Yale University, Open Yale Courses
This second lecture is about exoplanets; professor Bailyn insists about the impossibility to observe directly these planets, because they are too close of their star. The lecture begins at the 6th minute (before that he talks about the problem set). How to convert angular separation into distance. A large part is about scientific notation and some related algebra tips because the calculator is not allowed during tests (!).
See other lectures in this series.
This second lecture is about exoplanets; professor Bailyn insists about the impossibility to observe directly these planets, because they are too close of their star. The lecture begins at the 6th minute (before that he talks about the problem set). How to convert angular separation into distance. A large part is about scientific notation and some related algebra tips because the calculator is not allowed during tests (!).
See other lectures in this series.
Ruben's Tube
Classic physics experiment involving sound, a tube of propane and fire. He begins with sound at 449 Hz, then higher frequencies, then some jazz and then some rock.
Direct Current Electric Motor
DC electric motor. The magnetic force is represented in green, the magnetic field is in red, and the conventional current is in light pink.
Other animations by Yves Pelletier
Other animations by Yves Pelletier
Tokamak
A tokamak uses a magnetic field to confine a plasma.
Tokamak overview:
Tokamak history (by ITER):
Tokamak overview:
Tokamak history (by ITER):
Friday, 7 January 2011
How a loudspeaker works
Sound generation by a loudspeaker. The alternating current being applied to the loudspeaker causes the mechanical oscillation of a coil connected with cone of the loudspeaker. As a result of this oscillation some regions of the air turn out to be compressed, while the other regions are rarefied. The regions with excessive pressure are propagating in the space in the form of longitudinal waves. When such a wave reaches the ear, it forces the eardrum to be oscillated and we hear the sound.
Car on a Banked Track
The forces acting on a car undergoing circular motion on a banked track are illustrated from variety of viewpoints.
Other animations by Penn State Schuylkill
Other animations by Penn State Schuylkill
Kinematics in 2D
This animation illustrates the role of acceleration in 2D kinematics. The parallel component of acceleration (relative to velocity) speeds and slows the object while the perpendicular component changes the direction fo the velocity for turns.
Other animations by Penn State Schuylkill
Other animations by Penn State Schuylkill
Richard Garriott Space Video Blog: Conservation of Momentum
Demonstrations of conservation of momentum inside the international space station.
Two dimensional inelastic collision
Two dimensional inelastic collision. Both objects have the same mass, but initial velocities are not the same. Momentum is conserved, but kinetic energy decreases.
Other animations by Yves Pelletier.
Other animations by Yves Pelletier.
Direct Current versus Alternating Current
Difference between direct current (DC: The electric charge flows in a constant direction) and alternating current (AC: the motion of charge changes direction periodically).
Other animations by Penn State Schuylkill
Other animations by Penn State Schuylkill
Full Wave Rectification with a Diode Bridge
This animation shows the conventional flow of current during full wave rectification using a diode bridge. At the input, the current changes direction periodically. At the output, the current always flow in the same direction.
Other animations by Penn State Schuylkill
Other animations by Penn State Schuylkill
Thursday, 6 January 2011
Wednesday, 5 January 2011
MIT 8.01 Classical Mechanics Lecture 1
MIT Physics Course
Powers of 10, dimensional analysis, uncertainty of measurement, comparison between femurs of various animals (scaling arguments).
See other videos in this series.
Professor Walter Lewin
8.01 Physics I: Classical Mechanics, Fall 1999
8.01 Physics I: Classical Mechanics, Fall 1999
Powers of 10, dimensional analysis, uncertainty of measurement, comparison between femurs of various animals (scaling arguments).
See other videos in this series.
Standing Wave
Interference between two waves traveling in opposite directions (green and cyan) in a string whose ends are both fixed produce a standing wave (yellow). This is the fourth mode of vibration, with 2 wavelength across the string.
Other animations by Yves Pelletier
Other animations by Yves Pelletier
Chaotic Motion of a Double Pendulum
A double jointed pendulum hangs from a rod. Swinging the pendulum with high energy results in motion that cycles chaotically between normal modes. Swinging it with low energy results in more predictable motion. When viewed under black lights, it is easy to see that the first joint of the pendulum travels in a semicircular path, while the second joint follows varied, unpredictable trajectories.
Source: MIT TechTV
Source: MIT TechTV
One dimensional motion with constant acceleration
Graphs of position, velocity and acceleration in funciton of time for an object thrown upward vertically (air resistance is neglected).
- The acceleration vs time graph is an horizontal line, because acceleration is a constant (-9,8 m/s^2).
- The velocity vs time graph is a straight line; its slope is negative, because this slope equals the acceleration.
- The position vs time graph is a parabola. The slope of the tangent equals the velocity.
Mechanical resonance experiment with a pendulum
This is an experiment to find the resonant frequency of a pendulum. The string is 25 cm long: it is easy to calculate its natural frequency (about 1 Hz). First, the pendulum oscillates freely. With a chronometer, you can measure its frequency (1 Hz). Then a vibrator cause a forced oscillation. The oscillator's frequency is varied from 0.7 Hz to 1.3 Hz. The amplitude reach its maximum value at 1 Hz.
Simple harmonic motion (position vs time graph)
An object suspended to a spring is in simple harmonic motion. The position vs time graph is a sine.
Other animations by this author can be purchased here.
Other animations by this author can be purchased here.
Tuesday, 4 January 2011
Thin Film Interference: anti-reflecting coating
This animation illustrates destructive thin-film interference (which can be applied to anti-reflecting coating). The yellow wave is incident light (in air). When it reaches a substance with a higher refractive index (here n = 1,5), part of the light is reflected transmitted (shown in yellow: the wavelength becomes shorter) and part of the light if reflected with a 180° shift(shown in green). If the third medium (at the bottom) has a refractive index higher than 1.5, part of the transmitted light is reflected with a 180° shift (shown in pink). The reflected waves cancel each other (destructive interference) if the thin film has a proper thickness.
Monday, 3 January 2011
MIT Physics Demo -- Conductivity of Ionized Water
De-ionized water doesn't conduct electricity. When salt is added, water becomes conductive.
Source: MIT TechTV
See other MIT physics demos
Source: MIT TechTV
See other MIT physics demos
Sunday, 2 January 2011
Yale: Frontiers and Controversies in Astrophysics, Lecture 1
Professor Bailyn introduces the course and discusses the course material and requirements. The three major topics that the course will cover are exoplanets, black holes and dark energy. Class proper begins (at about 20:00) with a discussion on planetary orbits. A brief history of astronomy is also given and its major contributors over the centuries are introduced: Ptolemy, Galileo, Copernicus, Kepler, and Newton.
See other lectures in this series.
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