Động năng và thế năng - Bài tập nâng cao

Home Lớp 10 Vật lý 10 - Sách kết nối tri thức Bài 25. Động năng và thế năng.Bài tập nâng cao

{"common":{"save":0,"post_id":"8778","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"8225","mon_id":"1158790","chapter_id":"1159772","post_id":"8778","question":"M\u1ed9t v\u1eadt kh\u1ed1i l\u01b0\u1ee3ng 1 kg \u0111ang \u1edf cách m\u1eb7t \u0111\u1ea5t m\u1ed9t kho\u1ea3ng H = 20 m. \u1ede chân \u0111\u01b0\u1eddng th\u1eb3ng \u0111\u1ee9ng \u0111i qua v\u1eadt có m\u1ed9t cái h\u1ed1 sâu h = 5 m. Cho g = 10 m\/s². Tính th\u1ebf n\u0103ng c\u1ee7a v\u1eadt khi g\u1ed1c th\u1ebf n\u0103ng \u1edf \u0111áy h\u1ed3.<\/p>","options":["A.<\/strong> 100 J","B.<\/strong> 200 J","C.<\/strong> 250 J","D.<\/strong> 300 J"],"correct":"3","level":"3","hint":"","answer":"Ch\u1ecdn C.<\/strong> 250 J.<\/span><\/p>V\u1edbi g\u1ed1c th\u1ebf n\u0103ng \u1edf \u0111áy h\u1ed3, ta có: z = h + H = 5 + 20 = 25 (m).<\/p>Th\u1ebf n\u0103ng c\u1ee7a v\u1eadt là $W_t=mgz=1.10.25=250\\;(J)$<\/span>.<\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2025-04-07 09:08:43","option_type":"txt","len":0},{"id":"8228","mon_id":"1158790","chapter_id":"1159772","post_id":"8778","question":"M\u1ed9t v\u1eadt có kh\u1ed1i l\u01b0\u1ee3ng 3 kg \u0111\u01b0\u1ee3c \u0111\u1eb7t \u1edf m\u1ed9t v\u1ecb trí trong tr\u1ecdng tr\u01b0\u1eddng và th\u1ebf n\u0103ng t\u1ea1i v\u1ecb trí \u0111ó b\u1eb1ng $W_{t1}=600\\;J$<\/span>. Th\u1ea3 cho v\u1eadt r\u01a1i t\u1edbi m\u1eb7t \u0111\u1ea5t, t\u1ea1i \u0111ó th\u1ebf n\u0103ng c\u1ee7a v\u1eadt b\u1eb1ng ${W_t}_2=-900\\;J$<\/span>. H\u1ecfi v\u1eadt r\u01a1i t\u1eeb \u0111\u1ed9 cao nào so v\u1edbi m\u1eb7t \u0111\u1ea5t?<\/p>","options":["A.<\/strong> 20 m","B.<\/strong> 30 m","C.<\/strong> 10 m","D.<\/strong> 50 m"],"correct":"4","level":"3","hint":"","answer":"Ch\u1ecdn D.<\/strong> 50 m.<\/span><\/p>\u0110\u1ed9 cao c\u1ee7a v\u1ecb trí th\u1ea3 r\u01a1i v\u1eadt so v\u1edbi  m\u1ed1c th\u1ebf n\u0103ng: $z_1=\\dfrac{W_{t1}}{mg}=\\dfrac{600}{3.10}=20\\;(m)$<\/span>.<\/p>\u0110\u1ed9 cao c\u1ee7a m\u1ed1c th\u1ebf n\u0103ng so v\u1edbi m\u1eb7t \u0111\u1ea5t: $z_2=\\dfrac{|W_{t2}|}{mg}=\\dfrac{900}{3.10}=30\\;(m)$<\/span>.<\/p>\u0110\u1ed9 cao c\u1ee7a v\u1ecb trí th\u1ea3 r\u01a1i v\u1eadt so v\u1edbi m\u1eb7t \u0111\u1ea5t: $z=z_1+z_2=20+30=50\\;(m)$<\/span>.<\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2025-04-07 09:18:41","option_type":"txt","len":0},{"id":"8231","mon_id":"1158790","chapter_id":"1159772","post_id":"8778","question":"Treo m\u1ed9t v\u1eadt n\u1eb7ng vào m\u1ed9t lò xo l\u1ef1c k\u1ebf, kim l\u1ef1c k\u1ebf ch\u1ec9 s\u1ed1 4. Tính th\u1ebf n\u0103ng c\u1ee7a lò xo l\u1ef1c k\u1ebf lúc này, bi\u1ebft l\u1ef1c k\u1ebf chia \u0111\u1ed9 ra Newton và kho\u1ea3ng cách gi\u1eefa hai \u0111\u1ed9 chia li\u1ec1n nhau là 5 mm.<\/p>","options":["A.<\/strong> 20 mJ","B.<\/strong> 40 mJ","C.<\/strong> 30 mJ","D.<\/strong> 10 mJ"],"correct":"2","level":"3","hint":"","answer":"Ch\u1ecdn B.<\/strong> 40 mJ.<\/span><\/p>L\u1ef1c k\u1ebf chia \u0111\u1ed9 ra Newton ngh\u0129a là kho\u1ea3ng cách gi\u1eefa hai \u0111\u1ed9 chia liên ti\u1ebfp \u1ee9ng v\u1edbi l\u1ef1c \u0111àn h\u1ed3i c\u1ee7a lò xo là 1 N.<\/p>Ta có $F_{\u0111h}=4(N)$<\/span>; $\\Delta l=4.0,005=0,02(m)$<\/span>.<\/p>Suy ra \u0111\u1ed9 c\u1ee9ng c\u1ee7a lò xo: $k=\\dfrac{F_{\u0111h}}{\\Delta l}=\\dfrac{4}{0,02}=200(N\/m)$<\/span>.<\/p>Th\u1ebf n\u0103ng \u0111àn h\u1ed3i c\u1ee7a lò xo là: $W_t=\\dfrac{1}{2}.k.(\\Delta l)^2=\\dfrac{1}{2}.200.0,02^2=0,04J=40mJ$<\/span>.<\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2025-04-07 09:34:41","option_type":"txt","len":0}]}