Phản xạ âm, chống ô nhiễm tiếng ồn

Home Lớp 7 Khoa học tự nhiên 7 - Sách kết nối tri thức Bài 14: Phản xạ âm, chống ô nhiễm tiếng ồnBài tập trung bình

{"common":{"save":0,"post_id":"6277","level":2,"total":10,"point":10,"point_extra":0},"segment":[{"id":"9733","post_id":"6277","mon_id":"1158739","chapter_id":"1158740","question":"Nh\u1eefng v\u1eadt nào sau \u0111ây có kh\u1ea3 n\u0103ng ph\u1ea3n x\u1ea1 âm t\u1ed1t?<\/p>","options":["A. T\u1ea5m thép, bông.","B. V\u1ea3i nhung, x\u1ed1p.","C. Vách \u0111á, t\u1ea5m thép.","D. V\u1ea3i len, t\u1ea5m kính."],"correct":"3","level":"2","hint":"Vâ\u0323t liê\u0323u c\u01b0\u0301ng co\u0301 bê\u0300 m\u0103\u0323t nh\u0103\u0303n thi\u0300 pha\u0309n xa\u0323 âm tô\u0301t.<\/p>","answer":"A sai vi\u0300 bông pha\u0309n xa\u0323 âm ke\u0301m. B sai vi\u0300 xô\u0301p pha\u0309n xa\u0323 âm ke\u0301m. D sai vi\u0300 len pha\u0309n xa\u0323 âm ke\u0301m. \u0110áp án \u0111úng: C. Vách \u0111á, t\u1ea5m thép.<\/strong><\/span>  <\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"147","test":"0","date":"2022-09-24 11:10:05","option_type":"txt","len":2},{"id":"9734","post_id":"6277","mon_id":"1158739","chapter_id":"1158740","question":"Sau khi nghe ti\u1ebfng s\u1ea5m r\u1ec1n trong c\u01a1n dông, em h\u1ecdc sinh \u0111ã gi\u1ea3i thích nh\u01b0 sau. Câu nào \u0111úng nh\u1ea5t?<\/p>","options":["A. Vì th\u1eddi gian truy\u1ec1n âm thanh t\u1eeb ngu\u1ed3n phát ra âm thanh \u0111\u1ebfn m\u1eb7t \u0111\u1ea5t l\u1edbn h\u01a1n 1 giây.","B. Do ngu\u1ed3n âm phát ra t\u1eeb r\u1ea5t xa.","C. Tia sét (ngu\u1ed3n âm) chuy\u1ec3n \u0111\u1ed9ng do \u0111ó kho\u1ea3ng cách t\u1eeb ngu\u1ed3n âm \u0111\u1ebfn tai nghe thay \u0111\u1ed5i nên có ti\u1ebfng r\u1ec1n.","D. S\u1ea5m r\u1ec1n là do s\u1ef1 ph\u1ea3n x\u1ea1 c\u1ee7a âm t\u1eeb các \u0111ám mây dông trên b\u1ea7u tr\u1eddi xu\u1ed1ng m\u1eb7t \u0111\u1ea5t."],"correct":"4","level":"2","hint":"Âm pha\u0309n xa\u0323 la\u0300 âm dô\u0323i la\u0323i khi g\u0103\u0323p vâ\u0323t ca\u0309n.<\/p>","answer":"S\u1edf d\u0129 có ti\u1ebfng s\u1ea5m r\u1ec1n trong c\u01a1n dông là do s\u1ef1 ph\u1ea3n x\u1ea1 c\u1ee7a âm t\u1eeb các \u0111ám mây dông trên b\u1ea7u tr\u1eddi xu\u1ed1ng m\u1eb7t \u0111\u1ea5t. \u0110áp án \u0111úng: D. S\u1ea5m r\u1ec1n là do s\u1ef1 ph\u1ea3n x\u1ea1 c\u1ee7a âm t\u1eeb các \u0111ám mây dông trên b\u1ea7u tr\u1eddi xu\u1ed1ng m\u1eb7t \u0111\u1ea5t.<\/strong><\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"147","test":"0","date":"2022-09-24 11:11:04","option_type":"txt","len":3},{"id":"9735","post_id":"6277","mon_id":"1158739","chapter_id":"1158740","question":"M\u1ed9t ng\u01b0\u1eddi \u0111\u1ee9ng \u1edf g\u1ea7n vách núi \u0111á và g\u1ecdi to h\u01b0\u1edbng v\u1ec1 phía núi thì th\u1ea5y kho\u1ea3ng th\u1eddi gian t\u1eeb lúc g\u1ecdi \u0111\u1ebfn lúc nghe \u0111\u01b0\u1ee3c ti\u1ebfng v\u1ecdng l\u1ea1i là 4 s. Bi\u1ebft t\u1ed1c \u0111\u1ed9 truy\u1ec1n âm thanh trong không khí là 340 m\/s. Tính kho\u1ea3ng cách t\u1eeb ng\u01b0\u1eddi \u0111ó \u0111\u1ebfn vách núi.<\/p>","options":["A. 1360 m.","B. 170 m.","C. 85 m.","D. 680 m."],"correct":"4","level":"2","hint":"Qua\u0303ng \u0111\u01b0\u01a1\u0300ng truyê\u0300n âm = 2 khoa\u0309ng ca\u0301ch t\u01b0\u0300 nguô\u0300n âm t\u01a1\u0301i n\u01a1i nghe thâ\u0301y âm.<\/p>","answer":"Go\u0323i khoa\u0309ng ca\u0301ch t\u01b0\u0300 ng\u01b0\u01a1\u0300i \u0111ê\u0301n va\u0301ch nu\u0301i la\u0300 d (m). Qua\u0303ng \u0111\u01b0\u01a1\u0300ng truyê\u0300n âm t\u01b0\u0300 ng\u01b0\u01a1\u0300i t\u01a1\u0301i va\u0301ch nu\u0301i rô\u0300i pha\u0309n xa\u0323 la\u0323i t\u01b0\u0300 va\u0301ch nu\u0301i t\u01a1\u0301i ng\u01b0\u01a1\u0300i la\u0300 s = 2d (m) Ma\u0300 s = v.t = 340.4 = 1360 m   $\\Rightarrow d=\\frac{s}{2}=\\frac{1360}{2}=680 m$<\/span> \u0110áp án \u0111úng: D. 680 m.<\/strong><\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"147","test":"0","date":"2022-09-24 11:13:31","option_type":"txt","len":0}]}