L'étoile Sirius est l'étoile la plus brillante lorsqu'on observe le ciel. Elle est située à environ 86 000 000 000 000 km de la Terre. 1) À combien d'années-lumière Sirius est-elle située de la Terre ? 2) Quelle durée la lumière de Sirius met-elle pour nous parvenir ?

Astone is thrown with a speed v0 and returns to earth, as the drawing shows. ignore friction and air resistance, and consider the initial and final locations of the stone. which one of the following correctly describes the change δpe in the gravitational potential energy and the change δke in the kinetic energy of the stone as it moves from its initial to its final location? options a.δpe = 0 j and δke = 0 j b.δpe is positive and δke is negative c.δpe = 0 j and δke is positive d.δpe is negative and δke is positive e.δpe = 0 j and δke is negative