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Group 1 A. B. C. D. On lance une pièce en l’air: elle monte en passant par A, change de sens au sommet B, puis redescend via C. A quel point l’accélération est-elle minimale? A B C il n’y a pas de minimum Group 2 Un objet ponctuel en mouvement, de masse m est soumis à une force F non nulle. À t=0 la force s’anulle subitent. L’objet: A. B. C. D. Ralentit progressivement Continue d’avancer a vitesse constante S’arrête immediatement Ralentit puis inverse son mouvement Group 3 Je pouse une caisse sur un sol rugueux.Elle se déplace à vitesse constante. Quelles affirmations sont vraie ? 1 - j exerce une force constante non nulle sur la caisse 2 la somme des forces agissant sur la caisse est nulle A. B. C. D. 1 2 1 et 2 Ni 1 ni 2 Group 4 An apple is thrown upward vertically and then falls down. What can be said about the force acting on the apple during its motion A. The force is always zero B. The force is always directed upward C. The force is first directed upward then downward D. The force is always directed downward Group 5 Two hockey pucks are at rest on ice are attached by a massless string. A force F is applied on puck 1. Which is the direction of the force F’ on puck 2? Group 6 Alex throws a ball vertically with an initial velocity vA. It reaches its maximum height at point B. Neglecting air friction, what are velocity vB and acceleration aB at point B in Alex’s frame. A. B. C. D. vB = 0, aB = 0 vB = vA, aB = g vB = 0, aB = g vB = vA, aB = 0