Định luật III Newton

Home Lớp 10 Vật lý 10 - Sách kết nối tri thức Bài 16: Định luật III NewtonBài tập nâng cao

{"common":{"save":0,"post_id":"8475","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"7637","mon_id":"1158790","chapter_id":"1158796","post_id":"8475","question":"Hai qu\u1ea3 bóng ép sát vào nhau trên m\u1eb7t ph\u1eb3ng ngang. Khi buông tay, hai qu\u1ea3 bóng l\u0103n \u0111\u01b0\u1ee3c nh\u1eefng quãng \u0111\u01b0\u1eddng 9 m và 4 m r\u1ed3i d\u1eebng l\u1ea1i. Bi\u1ebft sau khi r\u1eddi nhau, hai qu\u1ea3 bóng chuy\u1ec3n \u0111\u1ed9ng ch\u1eadm d\u1ea7n \u0111\u1ec1u v\u1edbi gia t\u1ed1c không \u0111\u1ed5i. Tính t\u1ec9 s\u1ed1 kh\u1ed1i l\u01b0\u1ee3ng c\u1ee7a hai qu\u1ea3 bóng?<\/p>","options":["A.<\/strong> $m_1=\\dfrac{3}{2}m_2$<\/span>","B.<\/strong> $m_2=\\dfrac{9}{4}m_1$<\/span>","C.<\/strong> $m_2=\\dfrac{3}{2}m_1$<\/span>","D.<\/strong> $m_2=\\dfrac{2}{3}m_1$<\/span>"],"correct":"2","level":"3","hint":"Hai qu\u1ea3 bóng có cùng th\u1eddi gian chuy\u1ec3n \u0111\u1ed9ng nên t\u1ec9 s\u1ed1 gia t\u1ed1c chính là t\u1ec9 s\u1ed1 quãng \u0111\u01b0\u1eddng.<\/p>V\u1eadn d\u1ee5ng \u0111\u1ecbnh lu\u1eadt II và III Newton.<\/p>","answer":"Ch\u1ecdn B.<\/strong> $m_2=\\dfrac{9}{4}m_1$<\/span>.<\/span><\/p>Ta có:<\/p>$s_1=v_0t+\\dfrac{1}{2}a_1t^2=\\dfrac{1}{2}a_1t^2=9$<\/span>  (1).<\/p>$s_2=v_0t+\\dfrac{1}{2}a_2t^2=\\dfrac{1}{2}a_2t^2=4$<\/span>  (2).<\/p>Xét t\u1ec9 s\u1ed1 $\u200b\u200b\\dfrac{s_1}{s_2}=\\dfrac{a_1}{a_2}=\\dfrac{9}{4}$<\/span>.<\/p>Theo \u0111\u1ecbnh lu\u1eadt II Newton: $m=\\dfrac{F}{a}$<\/span>.<\/p>Theo \u0111\u1ecbnh lu\u1eadt III Newton: $F_1=F_2$<\/span> ⇒ $\\dfrac{m_2}{m_1}=\\dfrac{a_1}{a_2}=\\dfrac{9}{4}$<\/span> ⇒ $m_2=\\dfrac{9}{4}m_1$<\/span>.<\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2025-02-23 14:59:45","option_type":"math","len":0},{"id":"7643","mon_id":"1158790","chapter_id":"1158796","post_id":"8475","question":"M\u1ed9t xe l\u0103n b\u1eb1ng g\u1ed7 có kh\u1ed1i l\u01b0\u1ee3ng m = 300 g \u0111ang chuy\u1ec3n \u0111\u1ed9ng v\u1edbi v\u1eadn t\u1ed1c v = 3 m\/s thì va ch\u1ea1m vào m\u1ed9t xe l\u0103n b\u1eb1ng thép có kh\u1ed1i l\u01b0\u1ee3ng m = 600 g \u0111ang \u0111\u1ee9ng yên trên bàn nh\u1eb5n n\u1eb1m ngang. Sau th\u1eddi gian va ch\u1ea1m 0,2 s xe l\u0103n thép \u0111\u1ea1t v\u1eadn t\u1ed1c 0,5 m\/s theo h\u01b0\u1edbng c\u1ee7a v. Xác \u0111\u1ecbnh l\u1ef1c F tác d\u1ee5ng vào xe l\u0103n g\u1ed7 khi t\u01b0\u01a1ng tác và v\u1eadn t\u1ed1c c\u1ee7a nó ngay sau khi va ch\u1ea1m?<\/p>","options":["A.<\/strong> 1,5 N, 2 m\/s.","B.<\/strong> 2 N, 3 m\/s.","C.<\/strong> 2 N, 2 m\/s.","D.<\/strong> 1,5 N, 3 m\/s."],"correct":"1","level":"3","hint":"V\u1eadn d\u1ee5ng \u0111\u1ecbnh lu\u1eadt II và III Newton.<\/p>$F_{12}=F_{21}$<\/span><\/p>","answer":"Ch\u1ecdn A.<\/strong> 1,5 N, 2 m\/s.<\/span><\/p>Ch\u1ecdn chi\u1ec1u d\u01b0\u01a1ng là chi\u1ec1u chuy\u1ec3n \u0111\u1ed9ng ban \u0111\u1ea7u c\u1ee7a xe l\u0103n b\u1eb1ng g\u1ed7.<\/p>Kí hi\u1ec7u xe l\u0103n g\u1ed7 là 1, xe l\u0103n thép là 2.<\/p>Áp d\u1ee5ng \u0111\u1ecbnh lu\u1eadt III Newton:<\/p>$F_{12}=|-F_{21}|=m_2.a_2=m_2.\\dfrac{v_2-v_{02}}{t}=0,6.\\dfrac{0,5-0}{0,2}=1,5\\;(N)$<\/span>.<\/p>V\u1eady l\u1ef1c F tác d\u1ee5ng vào xe l\u0103n g\u1ed7 khi t\u01b0\u01a1ng tác là 1,5 N.<\/p>M\u1eb7t khác: $m_1.a_1=-m_2.a_2$<\/span> ⇔ $m_1.\\dfrac{v_1-v_{01}}{t}=-m_2.\\dfrac{v_2-v_{02}}{t}$<\/span>.<\/p>Thay s\u1ed1 vào ta \u0111\u01b0\u1ee3c: $0,3.\\dfrac{v_1-3}{0,2}=-0,6.\\dfrac{0,5-0}{0,2}$<\/span>⇒ $v_1=2$<\/span> (m\/s).<\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2025-02-23 15:10:23","option_type":"txt","len":2},{"id":"7645","mon_id":"1158790","chapter_id":"1158796","post_id":"8475","question":"M\u1ed9t v\u1eadt n\u1eb1m yên trên m\u1eb7t bàn \u0111\u01b0\u1ee3c là do<\/p>","options":["A.<\/strong> v\u1eadt ch\u1ec9 ch\u1ecbu tác d\u1ee5ng c\u1ee7a l\u1ef1c hút c\u1ee7a trái \u0111\u1ea5t.","B.<\/strong> không có l\u1ef1c nào tác d\u1ee5ng lên v\u1eadt.","C.<\/strong> các l\u1ef1c tác d\u1ee5ng lên v\u1eadt có c\u01b0\u1eddng \u0111\u1ed9 quá nh\u1ecf.","D.<\/strong> l\u1ef1c hút c\u1ee7a trái \u0111\u1ea5t tác d\u1ee5ng lên v\u1eadt cân b\u1eb1ng v\u1edbi ph\u1ea3n l\u1ef1c c\u1ee7a bàn."],"correct":"4","level":"3","hint":"V\u1eadn d\u1ee5ng \u0111\u1ecbnh lu\u1eadt III Newton: Khi v\u1eadt A tác d\u1ee5ng lên v\u1eadt B m\u1ed9t l\u1ef1c, thì v\u1eadt B c\u0169ng tác d\u1ee5ng tr\u1edf l\u1ea1i v\u1eadt A m\u1ed9t l\u1ef1c. Hai l\u1ef1c này là hai l\u1ef1c tr\u1ef1c \u0111\u1ed1i.<\/p>","answer":"Ch\u1ecdn D.<\/strong> l\u1ef1c hút c\u1ee7a trái \u0111\u1ea5t tác d\u1ee5ng lên v\u1eadt cân b\u1eb1ng v\u1edbi ph\u1ea3n l\u1ef1c c\u1ee7a bàn.<\/span><\/p>M\u1ed9t v\u1eadt n\u1eb1m yên trên m\u1eb7t bàn \u0111\u01b0\u1ee3c là do l\u1ef1c hút c\u1ee7a trái \u0111\u1ea5t tác d\u1ee5ng lên v\u1eadt cân b\u1eb1ng v\u1edbi ph\u1ea3n l\u1ef1c c\u1ee7a bàn.<\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2025-02-23 15:14:04","option_type":"txt","len":3}]}