2020½ìÄþÏÄÒø´¨ÌÆáâ»ØÃñÖÐѧ¸ßÈýÏÂѧÆÚµÚÈý´ÎÄ£Ä⿼ÊÔÀí×ÛÊÔÌâ ÏÂÔØ±¾ÎÄ

¸ßÈýÀí×ÛÈýÄ£ÎïÀí²Î¿¼´ð°¸

14C15B16B17B18B19BC20CD21AC

22. 8 20 B

23.£¨1£©AEDC£¨2·Ö£© 22 £¨2·Ö£© £¨2£©A2£¨2·Ö£© R1£¨1·Ö£©Æ«Ð¡£¨1·Ö£©

V A2 Rx R1 E 1

24. (1)Óɶ¯Äܶ¨ÀíÖªqEL£«¦Ì1mgL£½mv2 µÃE£½10 N/C.

20

(2)Òò»¬¿é¸ÕºÃÄܵ½´ïDµã£¬ÔòÓɶ¯Äܶ¨ÀíÖª

qEL£«¦Ì1mgL£«¦Ì2mgs£«mgR£½2mv¡ä20 µÃs£½1.0 m.

2

vG(3)É軬¿é»¬µ½CµãʱËÙ¶ÈΪv1£¬Òò»¬¿éÇ¡ºÃÄÜͨ¹ýGµã£¬ÔòÔÚGµãÓÐmg£½m

R1

112

´ÓCµ½GÓɶ¯Äܶ¨ÀíÖª£­mg¡¤2R£½mv2£­mv

2G21

112

´ÓAµ½CÓɶ¯Äܶ¨ÀíÖªqEL£«¦Ì1mgL£«¦Ì2mgs£½mv201£­mv1 2232ÁªÁ¢²¢´úÈëÊýÖµµÃv01£½62 m/s£½v

20

qB2d2?mm(2L?d)qBdqBd?25.(1)va? , vb? (2)t? (3)E0?

mL2qBqBd2mm

33£®½âÎö£º(1) £¨6·Ö£©ADE

(2) £¨9·Ö£©Éè´Ö¹ÜÖÐÆøÌåÎªÆøÌå1.ϸ¹ÜÖÐÆøÌåÎªÆøÌå2. ¶Ô´Ö¹ÜÖÐÆøÌå1£ºÓÐp0L1£½p1L1¡ä

ÓÒ²àÒºÃæÉÏÉýh1£¬×ó²àÒºÃæÏ½µh2£¬ÓÐS1h1£½S2h2£¬h1£«h2£½6 cm£¬ µÃh1£½2 cm£¬h2£½4 cm L1¡ä£½L1£­h1 ½âµÃ£ºp1£½90 cmHg

¶Ôϸ¹ÜÖÐÆøÌå2£ºÓÐp0L1£½p2L2¡ä p2£½p1£«¦¤h ½âµÃ£ºL2¡ä£½9.375 cm

ÒòΪh£½L1£«h2£­L2¡ä ½âµÃ£ºh£½6.625 cm

34. £¨1£©ADEÓÉÖʵãP×ö¼òгÔ˶¯µÄ±í´ïʽy?10sin5?tcm£¬¿ÉÖªÕâÁмòг²¨µÄÕñ·ùΪA?10cm£¬½ÇƵÂÊΪ??5?rads£¬ÔòÖÜÆÚΪ£ºT?2???0.4s£¬¹ÊAÕýÈ·£¬C´íÎó£»Óɲ¨µÄ´«²¥Ìصã¿ÉÖª£¬ÖʵãPÔÚ×ö¼òгÕñ¶¯£¬¹ÊB´íÎó£¬DÕýÈ·£»ÓÉͼ¶Á³ö²¨³¤Îª£º??4m£¬Ôò²¨ËÙΪ£ºv??T?4m?10ms£¬¹ÊEÕýÈ·¡£ ¹ÊÑ¡£ºADE 0.4s£¨2£©