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03:18 Bundesanstalt für Wasserbau (BAW) German 2010

Elbemodell Hamburger Yachthafen

Big container ships pass the marina of Hamburg, situated close to Wedel at the lower River Elbe, and affect the moored yachts with their bow and tail waves. A scale model of the River Elbe and the Hamburg marina was built up in the Hamburg office of the BAW. Water level, wave height and wave propagation during individual trips and encounters are measured in three dimensions and are analysed. A line jetty in front of the harbour entrance is a possible structural modification - as precise measuring methods showed - used in addition to a reduction of the ships' speed.
  • Published: 2010
  • Publisher: Bundesanstalt für Wasserbau (BAW)
  • Language: German
30:55 IWF (Göttingen) German 2008

Bioenergiedorf Jühnde - Der Weg zum Bioenergiedorf

In a group interview inhabitants of Jühnde and scientists from the Interdisciplinary Centre of Sustainable Development of the University of Göttingen tell the story of how Jühnde became a bionergy village. Experts explain the idea, the selection of the village, they remember the first delve of spade, the construction and operation of the bioenergy plant and discuss the economical, organisational and social aspects of this transformation.
  • Published: 2008
  • Publisher: IWF (Göttingen)
  • Language: German
16:06 IWF (Göttingen) English 2000

Ecology of the Hover Fly Episyrphus balteatus

The marmalade hoverfly, one of the most common hoverflies, feeds on nectar and pollen. In contrast, the larvae are carnivorous. Fertilised females search for aphid colonies to lay their eggs. Young larvae passively await the contact stimulation by an aphid, then attach themselves securely to the aphid and suck them dry. Larvae of the 3rd stage actively locate aphid colonies, glue the aphids to the substrate and to one another and then successively suck them dry. Two weeks after pupation the fly emerges. Macrophotography, slow-motion up to 400 times.
  • Published: 2000
  • Publisher: IWF (Göttingen)
  • Language: English
05:26 IWF (Göttingen) German 2003

Trägheit des Magnetfeldes: Induktive Schaltverzögerung

The switching on and off of electric devices is usually characterized by their instantaneous response. The presence of inductors with large self-inductance can, however, cause considerable delays. Iron cores can lead to additional delays resulting from a change of the magnetization. Such delays, extending over minutes, will be shown here. A large copper spool is wound on a heavy closed iron core. It can be connected with a switch to a 2 volt accumulator (lead-acid battery) and a projection ammeter of short response time (less than 1 sec). The time is measured with a large, hand-operated (historic) stopwatch. These experiments always are extremely surprising, considering that we tend to associate electric phenomena with the idea of the instantaneous, the timeless.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: German
01:21 IWF (Göttingen) German 2003

Bestimmung des elektrischen Erdfeldes

The electric field of the earth will be determined. A parallel plate capacitor of area 1 m2 is attached to the end of a long bamboo pole. The capacitor is connected to a ballistic galvanometer calibrated to measure current pulses (charges). On a balcony outside the lecture hall, the capacitor is held with its plates horizontal.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: German
07:36 IWF (Göttingen) German 2004

Stromlinien-Modellversuche

The goal is the demonstration of two-dimensional streamline patterns as they occur when non-viscous fluids flow around obstacles. The patterns shown are models, since they have been produced in a viscous fluid under conditions of laminar flow.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
01:59 IWF (Göttingen) German 2004

Maxwellsche Scheibe

A body that is being accelerated downward weighs less than when at rest. This is demonstrated with a flywheel on a shaft suspended on one arm of a household scale (Maxwell's disk). It is suspended on one arm of the scale with two strings which wrap around the thin shaft. When the flywheel is released, it accelerates downward, and the scale reads a reduced weight. During the subsequent rise (the flywheel still accelerating downward!) the scale again indicates a reduced weight.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
00:54 IWF (Göttingen) German 2004

Schwanke Achse

An object rotates stably around its axis of maximum moment of inertia, even if it is attached to a bent supple shaft. The experiment also shows that particles leave a rotating object by flying off in a tangential direction.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
01:22 IWF (Göttingen) German 2003

Zirkulare Schwingungen

Through superposition of the linear oscillations of two leaf springs of almost equal frequencies, linear, elliptic and circular oscillations can be generated and shown by optical projection.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: German
16:03 IWF (Göttingen) German 2000

Ökologie der Schwebfliege Episyrphus balteatus

Das Doppelbändchen, eine der häufigsten Schwebfliegen, ernährt sich von Nektar und Pollen. Die Larve dagegen lebt räuberisch. Begattete Weibchen suchen zur Eiablage Blattlauskolonien auf. Junge Larven erwarten passiv den Berührungsreiz einer Blattlaus, heften sich an der Laus fest und saugen sie aus. Larven des 3. Stadiums suchen aktiv Blattlauskolonien auf, verkleben die Läuse auf der Unterlage und untereinander und saugen sie nacheinander aus. 2 Wochen nach der Verpuppung schlüpft die Fliege. Makroaufnahmen, Zeitdehnung bis 400fach.
  • Published: 2000
  • Publisher: IWF (Göttingen)
  • Language: German
01:41 IWF (Göttingen) German 2004

Interpretation der Elektronendichte - beta-Faltblatt

The video clip shows the electron density measuring of a simple protein - the lysozyme from egg white - visualized by means of a special software (XTAL View).
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
1:02:54 IWF (Göttingen) German 2007

CELAN - Musiktheater in sieben Entwürfen (Teil 1)

The CELAN opera is the result of a long and intensive occupation of the composer Peter Ruzicka with the life and work of the Jewish poet Paul Celan (1920 - 1970). The opera premiered in the Dresden Semper Opera House in 2001. Its theme is a musical treatment of Celan's complex metaphoric system and his tragic biography. The IWF filmed a performance on March 2, 2002, which is presented here in its full length in two parts.
  • Published: 2007
  • Publisher: IWF (Göttingen)
  • Language: German
19:13 IWF (Göttingen) German 2007

CELAN - Musiktheater in sieben Entwürfen (Teil 2)

The CELAN opera is the result of a long and intensive occupation of the composer Peter Ruzicka with the life and work of the Jewish poet Paul Celan (1920 - 1970). The opera premiered in the Dresden Semper Opera House in 2001. Its theme is a musical treatment of Celan's complex metaphoric system and his tragic biography. The IWF filmed a performance on March 2, 2002, which is presented here in its full length in two parts.
  • Published: 2007
  • Publisher: IWF (Göttingen)
  • Language: German
13:56 IWF (Göttingen) German 1997

Stridulationsverhalten der Feldheuschrecke Omocestus viridulus

Omocestus viridulus, der Bunte Grashüpfer, ist ein typischer Vertreter der Feldheuschrecken der Unterfamilie Gomphocerinae mit gut entwickeltem akustischen Kommunikationsverhalten. Der Lautapparat besteht aus einer Reihe auf Resilinbasen gelenkig eingesetzter Zäpfchen an der Innenseite der Hinterschenkel, die über die vorstehende Radialader der Vorderflügel gestrichen werden. Der Film zeigt den Stridulationsapparat von Omocestus viridulus und die verschiedenen situationsbedingten Lautäußerungen im natürlichen Habitat, z. T. in 16facher Tonzeitdehnung.
  • Published: 1997
  • Publisher: IWF (Göttingen)
  • Language: German
13:56 IWF (Göttingen) English 1997

Stridulatory Behaviour of the Acridid Grasshopper Omocestus viridulus

Acoustic communication is well developed in acridid grasshoppers. Especially species of the subfamily Gomphocerinae display elaborate stridulatory behaviour. Their stridulatory apparatus consists of a row of cuticular pegs at the inside of each hindleg and an enhanced vein of the elytra. Species specific acoustic signals are produced by rhythmically rubbing the hindlegs against the elytra. The video demonstrates the stridulatory apparatus of Omocestus viridulus L. (Saltatoria, Acrididae) and shows the different leg movements and song types of the animals in their natural habitat.
  • Published: 1997
  • Publisher: IWF (Göttingen)
  • Language: English
06:26 IWF (Göttingen) German 2004

Wasserwellenexperimente

Some of the fundamental properties of waves are demonstrated using surface waves in a water trough.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
00:40 IWF (Göttingen) German 2003

Langsam ablaufender elastischer Stoß

Elastic collision between two bodies in slow motion through the proper choice of the experimental conditions. It will be shown that during the collision the kinetic energy is briefly converted into potential energy and then back into kinetic energy. The slow collision, achieved through the proper choice of masses and spring constants, demonstrates clearly the transformation from kinetic to potential energy, and back again, as is characteristic for elastic collisions. This experiment also demonstrates the conservation of linear momentum.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: German
02:03 IWF (Göttingen) German 2003

Zur Vektornatur des Drehimpulses

A ventilator which can rotate freely around a vertical axis can be used to demonstrate that the angular momentum is a vector. A ventilator is mounted so that it can rotate freely around a vertical axis. It can also be tilted so that the air is blown either horizontally or upward. Upon turning on the ventilator, both the propeller and the driven air jet receive an angular momentum. Its vector points in the direction of the jet, parallel to the axis of the propeller. The ventilator receives an equal angular momentum in the opposite direction (opposite sense of rotation). The experiment is carried out for two different orientations of the ventilator.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: German
00:56 IWF (Göttingen) German 2003

Präzession eines rotierenden Rades

A spinning top (gyroscope) does not follow a torque in the same way as, for example, a top at rest. Rather, it moves sideways, it "precesses". This startling behavior will be shown here. The top is a bicycle wheel with its rim filled with lead wire. It can be suspended on a rope dangling from the ceiling. The wheel is spun while holding its axle horizontal. Then, one end of the axle is attached to the rope. The weight of the wheel and the tension in the rope together cause a torque which, however, does not turn the axle into the vertical position, as would happen if the wheel were not spinning. Instead, the axle, which indicates the direction of the wheels angular momentum, circles on a horizontal plane around the point on which it is suspended. This sideways motion of a top under the influence of a torque is called "precession".
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: German
02:42 IWF (Göttingen) German 2003

Drehstuhlexperimente zur Erhaltung des Drehimpulses

Conservation of angular momentum around the vertical axis of a rotating chair. A man sitting on a rotating chair with very little friction uses weights, a spinning wheel, and a wooden hammer with a long handle to demonstrate the vector nature of the angular momentum as well as its conservation in the absence of external torques. This setup allows to limit the observation to a single (the vertical) component of the angular momentum.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: German
02:25 IWF (Göttingen) German 2004

Rotation um freie Achsen

It will be shown that the axis of maximum moment of inertia is also the most stable axis of free rotation. For this, objects of different shapes are suspended on thin wires from the vertical axis of an electric motor, and are rotated at increasing frequencies. They are a cylindrical metal rod, a piece of wood in the form of an egg, and a loose loop of a metal chain.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
01:21 IWF (Göttingen) German 2003

Dynamische Stabilität einer Fahrradkette

Belts made of soft material which are flexible while at rest, in this case a chain made of metal links, can become quite rigid, independent of their shape, when their tangential velocity is sufficiently large. This phenomenon is called "dynamic stability". Through the radial forces the chain stiffens, and after it gets thrown off the toothed wheel, it roles along the floor, jumps over a wooden beam, and collapses into its shapeless form only after coming to rest on the rug after colliding with the wall. It is clearly seen how the stiff chain deforms somewhat as it hits the beam. Note also how long the chain continues to rotate on the rug near the end of the experiment, before it finally comes to rest and collapses.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: German
01:10 IWF (Göttingen) German 2004

Freie Rotation eines quaderförmigen Körpers

Only the axes of maximum and minimum moment of inertia are free axes of rotation around which a body can rotate stably without mechanical support. Attempts at rotation around other axes lead to wobbling, i.e. unstable rotation. A piece of styrofoam in the form of a parallelepiped (like a cigar box) is thrown into the air while giving it a spin. In order to watch the motion, opposing surfaces have been marked with different colors.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
01:28 IWF (Göttingen) German 2004

Modell einer fortschreitenden Welle

The connection between circular motion, phase difference and wave propagation is shown with the help of a series of beads arranged to form a right-handed helix.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
00:44 IWF (Göttingen) German 2003

Impulserhaltungssatz

According to the law of the conservation of momentum, which states that in every closed system the sum of the individual momenta stays constant. They can be exchanged inside the system. Three examples will be shown. In all three cases, the total momentum of the closed system remains constant.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: German
01:19 IWF (Göttingen) German 2004

Zur Physik des Turnens mit Schwüngen

Using a torsional oscillator, it will be shown how its amplitude can be increased without external torques, merely by correctly timed variations of the moment of inertia, which requires work. This is the principle of setting a swing in motion, or of swinging on the high bar. The oscillator used is a rotating stool with a helical spring. The experimenter on the stool changes the moment of inertia by alternating his position from sitting to prone.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
04:49 IWF (Göttingen) German 2003

Freie und erzwungene Schwingungen eines Drehpendels (Pohlsches Rad)

Basic properties of harmonic oscillators on a torsional pendulum, specifically their free and driven oscillations. For the latter, the transient oscillations will be shown, before the steady state has been reached. The torsional pendulum consists of a circular copper ring with an eddy current brake, and a torsional spring. One end of the spring is attached to the copper ring, the other end to a motor via an eccentric-and-rod mechanism. For the experiment, another pendulum, also specifically designed for lecture demonstrations, will be used. It sits on an optical bench and is projected onto the front wall of the lecture hall, together with a meter indicating the exciting frequencies used for the driven oscillations. Two pointers, one attached to the pendulum, the other to the eccentric-and-rod mechanism used for moving the spring, allow observation of the phase difference between the exciting torque and the angular displacement of the pendulum.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: German
01:35 IWF (Göttingen) German 2004

Behnsches Rohr

A balloon filled with a gas lighter than air will rise. This is explained as evidence that the pressure in the heavier air decreases more rapidly with increasing height than that of the lighter gas inside the balloon.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
01:29 IWF (Göttingen) German 2003

Freier Fall

Free fall as an example for a movement with a constant tangential acceleration.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: German
00:55 IWF (Göttingen) German 2003

Plastische Verformung und Zerreißfestigkeit

The measurements performed in the experiment "Elastic deformation, Hooke's law" (C 14833) on a copper wire, which had been limited to elastic deformations at small stresses, will be extended here to larger stresses. When the yield stress is exceeded, plastic, i.e. irreversible deformation is observed. A further increase of the stress beyond the rupture strength, leads to rupture. A 40 cm long piece of wire is suspended on a lab stand, and carries a tray on which weights can be deposited. A pillow under the tray will dampen the fall when the wire ruptures. The loading of the tray occurs in three steps : First, 2 kg cause a clearly visible elongation. The addition of 1 kg results in a slow length change of several centimeters, the wire "flows", until "work hardening" leads to a constant elongation. The addition of only 200 g finally leads to rupture, as the rupture strength is exceeded.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: German
00:50 IWF (Göttingen) German 2003

Longitudinale Schwingung einer Spiralfeder

Longitudinal standing waves can be excited on helical springs. Through optical projection, nodes and antinodes are made visible. A horizontally mounted small helical spring is projected onto the wall of the lecture hall. A standing longitudinal wave is excited by driving one of its ends with a door bell vibrating at one of the normal mode frequencies of the spring. In the projection, the nodes and antinodes of the longitudinal vibration are easily seen: In the nodes, the sections of the spring are motionless and thus clearly imaged, while in the antinodes they appear fuzzy.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: German
02:03 IWF (Göttingen) German 2004

Trägheitsmomente

The moment of inertia of a body is determined by its mass and its distribution relative to the axis of rotation. An experimenter assumes different positions on the stool which has been converted to a torsional oscillator, and its period of oscillation is determined. From this measurement the moment of inertia can be obtained, and is found to differ by almost an order of magnitude for different positions.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
01:00 IWF (Göttingen) German 2004

Kugeltanz

A steel ball is dropped onto a heavy steel plate. It collides elastically with the plate and rises almost back to its initial height, whereupon the motion repeats itself periodically, with an amplitude determined by the initial height. The total force acting on the ball is highly nonlinear. Energy dissipation leads to a slow decrease of the mechanical energy, and thus of the amplitude, as the experiment progresses. At the same time, the frequency increases
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
01:50 IWF (Göttingen) German 2004

Bestimmung einer Geschossgeschwindigkeit

The large velocity of a bullet is determined using only a simple pendulum together with the knowledge of its motion, and the law of the conservation of momentum.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
01:33 IWF (Göttingen) German 2004

Lissajous-Bahnen

Lissajous figures are created and made visible with bending vibrations with different frequencies in two perpendicular directions, using a metal bar of rectangular cross section which is clamped at one end and carries a mirror at the other, off which a light beam is reflected.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
01:17 IWF (Göttingen) German 2003

Transversale Schwingung einer Saite

Vibrations of the strings of musical instruments are far more complicated than is commonly assumed. On such a string, a large number of higher harmonics of different amplitudes are usually superimposed (which may explain the difficulties for musicians to play a string instrument well). This complexity is also observable in the motion of sections of the string, as will be shown in this experiment. A violin string is stretched perpendicularly across an optical bench, and can be excited either by plucking, or by striking it with a bow. An arbitrary spot of the string is illuminated through a vertical slit, and is projected on the wall of the lecture hall. The string is plucked, as can be heard. The slit with the vibrating section of the string is shown on the projection screen. As the disk with the lenses is rotated, the time-dependent motion of the section is displayed. It is by no means a simple sinusoidal oscillation. Rather, the pictures show amazingly complicated patterns. Similar patterns are also obtained with a stroked string.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: German
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