File:Falling ball.jpg
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This is a featured picture on the Romanian language Wikipedia ( Imagini de calitate) and is considered one of the finest images.| Description |
English: An initially-stationary object which is allowed to fall freely under gravity drops a distance which is proportional to the square of the elapsed time. This image, spanning half a second, was captured with a stroboscopic flash at 20 flashes per second. During the first 1/20th of a second the ball drops one unit of distance (here, a unit is about 12 mm); by 2/20ths it has dropped at total of 4 units; by 3/20ths, 9 units and so on.
To take the picture, the ball - about the size of a tennis ball - was suspended by a short length of black thread and was released as the shutter was opened and the flash triggered. The shutter remained open for the whole of the half-second period, during which time the flash fired multiple times to capture the ball at 1/20 second intervals. Français :
Un objet en chute libre depuis une position fixe parcours une distance proportionnelle au carré du temps écoulé. Cette photo a été prise sur une période de 0,5 seconde avec un flash stroboscopique réglé sur 20 impulsions par seconde. La balle, de la taille d'une balle de tennis, était retenue pas un fil noir sectionne au moment ou l'exposition a commence et ou le flash produisit sa première impulsion lumineuse. Română: Un obiect staţionar lăsat în cădere liberă în câmpul gravitaţional al Pământului. Legea de mişcare este o funcţie de gradul al doilea, poziţia la fiecare moment fiind egală cu pătratul timpului scurs de la începutul căderii. Imaginea a fost expusă timp de 500 de milisecunde, cu un flash stroboscopic, declanşat cu o frecvenţă de 20 de flash-uri pe secundă. În primele 50 ms, mingea cade pe o unitate de distanţă (unitatea de distanţă este de aproximativ 12 mm—distanţa parcursă în 50 ms de un obiect lăsat liber în câmpul gravitaţional al Pământului de la o viteză iniţială de 0 m/s); după ce s-au scurs 100 ms, mingea a căzut 4 unităţi de distanţă; după 150 ms, mingea a parcurs 9 unităţi, şi aşa mai departe. Pentru realizarea imaginii, mingea (de dimensiunile unei mingi de tenis) a fost suspendată cu un fir negru şi a fost lăsată să cadă în momentul începerii expunerii şi odată cu primul bliţ. Aparatul a continuat să expună timp de o jumătate de secundă, timp în care bliţul s-a declanşat de mai multe ori, luminând mingea la intervale de 50 ms
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| Date | 20 October 2007 |
| Source | Own work |
| Author | MichaelMaggs |
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This is a retouched picture, which means that it has been digitally altered from its original version. Modifications: Dark background replaced with black; scale added; levels & contrast.
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This image has been assessed under the valued image criteria and is considered the most valued image on Commons within the scope: Object in free fall.. You can see its nomination at Commons:Valued image candidates/Falling ball.jpg.
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