{"common":{"save":0,"post_id":"8861","level":1,"total":10,"point":10,"point_extra":0},"segment":[{"id":"8374","mon_id":"1158790","chapter_id":"1159899","post_id":"8861","question":"<p>Công th\u1ee9c tính kh\u1ed1i l\u01b0\u1ee3ng riêng c\u1ee7a m\u1ed9t ch\u1ea5t là<\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$\\rho=m.V$<\/span>.","<strong>B.<\/strong> <span class=\"math-tex\">$\\rho=\\dfrac{m}{V}$<\/span>.","<strong>C.<\/strong> <span class=\"math-tex\">$\\rho=\\dfrac{V}{m}$<\/span>.","<strong>D.<\/strong> <span class=\"math-tex\">$\\rho=m^2.V$<\/span>."],"correct":"2","level":"1","hint":"","answer":"<p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>B.<\/strong> <span class=\"math-tex\">$\\rho=\\dfrac{m}{V}$<\/span>.<\/span><\/p><p>Công th\u1ee9c tính kh\u1ed1i l\u01b0\u1ee3ng riêng c\u1ee7a m\u1ed9t ch\u1ea5t là <span class=\"math-tex\">$\\rho=\\dfrac{m}{V}$<\/span>.<\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2025-04-16 08:31:30","option_type":"math","len":0},{"id":"8376","mon_id":"1158790","chapter_id":"1159899","post_id":"8861","question":"<p>Ba v\u1eadt làm b\u1eb1ng ba ch\u1ea5t khác nhau là \u0111\u1ed3ng, s\u1eaft, nhôm có kh\u1ed1i l\u01b0\u1ee3ng b\u1eb1ng nhau. Khi nhúng ng\u1eadp chúng vào n\u01b0\u1edbc thì l\u1ef1c \u0111\u1ea9y c\u1ee7a n\u01b0\u1edbc tác d\u1ee5ng vào v\u1eadt nào là l\u1edbn nh\u1ea5t?<\/p>","options":["<strong>A.<\/strong> \u0110\u1ed3ng.","<strong>B.<\/strong> Nhôm.","<strong>C.<\/strong> S\u1eaft.","<strong>D. <\/strong>C\u1ea3 3 v\u1eadt \u0111\u1ec1u nh\u01b0 nhau."],"correct":"2","level":"1","hint":"","answer":"<p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>B.<\/strong> Nhôm.<\/span><\/p><p>L\u1ef1c \u0111\u1ea9y c\u1ee7a n\u01b0\u1edbc: <span class=\"math-tex\">$F_A=\\rho_n gV$<\/span> (<span class=\"math-tex\">$\\rho_n$<\/span> là kh\u1ed1i l\u01b0\u1ee3ng riêng c\u1ee7a n\u01b0\u1edbc).<\/p><p>Mà <span class=\"math-tex\">$V=\\dfrac{m}{\\rho_v}$<\/span> ⇒ <span class=\"math-tex\">$F_A=\\rho_n g.\\dfrac{m}{\\rho_v}$<\/span> (<span class=\"math-tex\">$\\rho_v$<\/span> là kh\u1ed1i l\u01b0\u1ee3ng ri\u1ebfng c\u1ee7a v\u1eadt).<\/p><p>Vì các v\u1eadt \u0111\u1ec1u \u0111\u01b0\u1ee3c nhúng trong n\u01b0\u1edbc và có cùng kh\u1ed1i l\u01b0\u1ee3ng nên <span class=\"math-tex\">$F_A\\backsim\\dfrac{1}{\\rho_v}$<\/span>.<\/p><p>Mà <span class=\"math-tex\">$\\rho_{nh}< \\rho_s <\\rho_d$<\/span> nên l\u1ef1c \u0111\u1ea9y c\u1ee7a n\u01b0\u1edbc lên nhôm là l\u1edbn nh\u1ea5t.<\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2025-04-16 08:45:10","option_type":"txt","len":2},{"id":"8378","mon_id":"1158790","chapter_id":"1159899","post_id":"8861","question":"<p>M\u1ed9t th\u1ecfi nhôm và m\u1ed9t th\u1ecfi thép có th\u1ec3 tích b\u1eb1ng nhau cùng \u0111\u01b0\u1ee3c nhúng chìm trong n\u01b0\u1edbc. Nh\u1eadn xét nào sau \u0111ây là <strong>\u0111úng<\/strong>?<br \/><span style=\"color:#c0392b;\">(1) Th\u1ecfi nào chìm sâu h\u01a1n thì l\u1ef1c \u0111\u1ea9y Archimedes tác d\u1ee5ng lên th\u1ecfi \u0111ó l\u1edbn h\u01a1n.<\/span><br \/><span style=\"color:#16a085;\">(2) Thép có kh\u1ed1i l\u01b0\u1ee3ng riêng l\u1edbn h\u01a1n nhôm nên th\u1ecfi thép ch\u1ecbu tác d\u1ee5ng c\u1ee7a l\u1ef1c \u0111\u1ea9y Archimedes l\u1edbn h\u01a1n.<\/span><br \/><span style=\"color:#8e44ad;\">(3) Hai th\u1ecfi nhôm và thép \u0111\u1ec1u ch\u1ecbu tác d\u1ee5ng c\u1ee7a l\u1ef1c \u0111\u1ea9y Archimedes nh\u01b0 nhau vì chúng cùng \u0111\u01b0\u1ee3c nhúng trong n\u01b0\u1edbc nh\u01b0 nhau.<\/span><br \/><span style=\"color:#2980b9;\">(4) Hai th\u1ecfi nhôm và thép \u0111\u1ec1u ch\u1ecbu tác d\u1ee5ng c\u1ee7a l\u1ef1c \u0111\u1ea9y Archimedes nh\u01b0 nhau vì chúng chi\u1ebfm th\u1ec3 tích trong n\u01b0\u1edbc nh\u01b0 nhau.<\/span><\/p>","options":["<strong>A.<\/strong> Nh\u1eadn xét (1).","<strong>B.<\/strong> Nh\u1eadn xét (3).","<strong>C.<\/strong> Nh\u1eadn xét (2).","<strong>D.<\/strong> Nh\u1eadn xét (4)."],"correct":"4","level":"1","hint":"","answer":"<p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>D.<\/strong> Nh\u1eadn xét (4).<\/span><\/p><p>Khi v\u1eadt \u0111\u01b0\u1ee3c nhúng chìm trong ch\u1ea5t l\u1ecfng thì s\u1ebd ch\u1ecbu thêm tác d\u1ee5ng c\u1ee7a l\u1ef1c \u0111\u1ea9y Archimedes.<\/p><p>L\u1ef1c \u0111\u1ea9y Archimedes: <span class=\"math-tex\">$F_A=\\rho gV$<\/span> suy ra <span class=\"math-tex\">$F_A\\backsim V$<\/span><\/p><p>Các th\u1ecfi kim lo\u1ea1i có cùng th\u1ec3 tích và cùng \u0111\u01b0\u1ee3c nhúng trong n\u01b0\u1edbc nên \u0111\u1ed9 l\u1edbn l\u1ef1c \u0111\u1ea9y Archimedes tác d\u1ee5ng lên chúng là nh\u01b0 nhau.<\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2025-04-16 08:50:25","option_type":"txt","len":2}]}