{"common":{"save":0,"post_id":"8856","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"8315","mon_id":"1158790","chapter_id":"1159899","post_id":"8856","question":"<p>M\u1ed9t xe \u0111ua ch\u1ea1y quanh m\u1ed9t \u0111\u01b0\u1eddng tròn n\u1eb1m ngang, bán kính R. V\u1eadn t\u1ed1c xe không \u0111\u1ed5i. L\u1ef1c \u0111óng vai trò là l\u1ef1c h\u01b0\u1edbng tâm lúc này là<\/p>","options":["<strong>A.<\/strong> l\u1ef1c \u0111\u1ea9y c\u1ee7a \u0111\u1ed9ng c\u01a1.","<strong>B.<\/strong> l\u1ef1c hãm.","<strong>C.<\/strong> l\u1ef1c ma sát ngh\u1ec9.","<strong>D.<\/strong> l\u1ef1c c\u1ee7a vô – l\u0103ng (tay lái)."],"correct":"3","level":"3","hint":"","answer":"<p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>C.<\/strong> l\u1ef1c ma sát ngh\u1ec9.<\/span><\/p><p>M\u1ed9t xe \u0111ua ch\u1ea1y quanh m\u1ed9t \u0111\u01b0\u1eddng tròn n\u1eb1m ngang, bán kính R. V\u1eadn t\u1ed1c xe không \u0111\u1ed5i. L\u1ef1c \u0111óng vai trò là l\u1ef1c h\u01b0\u1edbng tâm lúc này là l\u1ef1c ma sát ngh\u1ec9.<\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2025-04-13 14:35:13","option_type":"txt","len":2},{"id":"8318","mon_id":"1158790","chapter_id":"1159899","post_id":"8856","question":"<p>Mô\u0323t vâ\u0323t nho\u0309 khô\u0301i l\u01b0\u01a1\u0323ng 250 g chuyê\u0309n \u0111ô\u0323ng tro\u0300n \u0111ê\u0300u trên quy\u0303 \u0111a\u0323o ba\u0301n ki\u0301nh 1,2 m. Biê\u0301t trong 1 phu\u0301t vâ\u0323t quay \u0111\u01b0\u01a1\u0323c 120 vo\u0300ng. \u0110ô\u0323 l\u01a1\u0301n l\u01b0\u0323c h\u01b0\u01a1\u0301ng tâm gây ra chuyê\u0309n \u0111ô\u0323ng tròn cu\u0309a vâ\u0323t la\u0300<\/p>","options":["<strong>A.<\/strong> 47,4 N","<strong>B.<\/strong> 3,8 N","<strong>C.<\/strong> 4,5 N","<strong>D.<\/strong> 46,4 N"],"correct":"1","level":"3","hint":"","answer":"<p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>A.<\/strong> 47,4 N.<\/span><\/p><p>T\u1ea7n s\u1ed1 c\u1ee7a v\u1eadt nh\u1ecf: <span class=\"math-tex\">$f=120:60=2(Hz)$<\/span>.<br \/>\u0110ô\u0323 l\u01a1\u0301n gia t\u1ed1c h\u01b0\u01a1\u0301ng tâm vâ\u0323t la\u0300 <span class=\"math-tex\">$a_{ht}=\\omega^2R=4\\pi^2f^2R=4\\pi^2.2^2.1,2\\approx189,5(m\/s^2)$<\/span>.<br \/>\u0110ô\u0323 l\u01a1\u0301n l\u01b0\u0323c h\u01b0\u01a1\u0301ng tâm gây ra chuyê\u0309n \u0111ô\u0323ng tro\u0300n cu\u0309a vâ\u0323t la\u0300<br \/><span class=\"math-tex\">$F_{ht}=ma_{ht}=0,25.189,5=47,375\\approx47,4(N)$<\/span>.<\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2025-04-13 14:41:16","option_type":"txt","len":0},{"id":"8320","mon_id":"1158790","chapter_id":"1159899","post_id":"8856","question":"<p>M\u1ed9t xe \u0111ua ch\u1ea1y quanh m\u1ed9t \u0111\u01b0\u1eddng tròn n\u1eb1m ngang, bán kính 250 m. V\u1eadn t\u1ed1c xe không \u0111\u1ed5i có \u0111\u1ed9 l\u1edbn là 50 m\/s. Kh\u1ed1i l\u01b0\u1ee3ng xe là 2000 kg. \u0110\u1ed9 l\u1edbn c\u1ee7a l\u1ef1c h\u01b0\u1edbng tâm c\u1ee7a chi\u1ebfc xe là:<\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$10N$<\/span>","<strong>B.<\/strong> <span class=\"math-tex\">$4.10^2N$<\/span>","<strong>C.<\/strong> <span class=\"math-tex\">$4.10^3N$<\/span>","<strong>D.<\/strong> <span class=\"math-tex\">$2.10^4N$<\/span>"],"correct":"4","level":"3","hint":"","answer":"<p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>D.<\/strong> <span class=\"math-tex\">$2.10^4N$<\/span>.<\/span><\/p><p>\u0110\u1ed9 l\u1edbn gia t\u1ed1c h\u01b0\u1edbng tâm c\u1ee7a xe là: <span class=\"math-tex\">$a_{ht}=v^2:R=50^2:250=10(m\/s^2)$<\/span>.<br \/>\u0110\u1ed9 l\u1edbn c\u1ee7a l\u1ef1c h\u01b0\u1edbng tâm c\u1ee7a chi\u1ebfc xe là: <span class=\"math-tex\">$F_{ht}=ma_{ht}=2000.10=2.10^4(N)$<\/span>.<\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2025-04-13 14:46:16","option_type":"math","len":0}]}