Question

6£®Èçͼ1Ëùʾ£¬Á½»¬¿éA¡¢BÓÃϸÏß¿ç¹ý¶¨»¬ÂÖÏàÁ¬£¬B¾àµØÃæÒ»¶¨¸ß¶È£¬A¿ÉÔÚϸÏßÇ£ÒýÏÂÑØ×ã¹»³¤µÄ´Ö²ÚбÃæÏòÉÏ»¬¶¯£®ÒÑÖªm_A=2kg£¬m_B=4kg£¬Ð±ÃæÇã½Ç¦È=37¡ã£®Ä³Ê±¿ÌÓɾ²Ö¹ÊÍ·ÅA£¬²âµÃAÑØбÃæÏòÉÏÔ˶¯µÄvÒ»tͼÏóÈçͼ2Ëùʾ£®ÒÑÖªg=10m/s2£¬sin 37¡ã=0.6£®Çó£º
£¨1£©AÓëбÃæ¼äµÄ¶¯Ä¦²ÁÒòÊý£»
£¨2£©AÑØбÃæÏòÉÏ»¬¶¯µÄ×î´óλÒÆ£»
£¨3£©»¬¶¯¹ý³ÌÖÐϸÏ߶ÔAµÄÀ­Á¦Ëù×öµÄ¹¦£®

Answer 1

·ÖÎö £¨1£©ÓÉͼÏóÇóµÃ¼ÓËٶȣ¬È»ºó¶ÔA¡¢B½øÐÐÊÜÁ¦·ÖÎö£¬ÓÉÅ£¶ÙµÚ¶þ¶¨ÂÉÁªÁ¢Çó½â£»
£¨2£©·ÖÎöBÂäµØºóAµÄÊÜÁ¦Çé¿ö£¬Ó¦ÓÃÅ£¶ÙµÚ¶þ¶¨ÂÉÇóµÃ¼ÓËٶȣ¬È»ºó¸ù¾ÝÔȱäËÙÔ˶¯Î»Òƹ«Ê½·Ö±ðÇóµÃ¼ÓËÙ¡¢¼õËÙ¹ý³ÌµÄλÒÆ£¬¼´¿Éµþ¼ÓµÃµ½×ÜλÒÆ£»
£¨3£©¶Ô¼ÓËÙ¹ý³Ì½øÐÐÊÜÁ¦·ÖÎö£¬È»ºóÓɶ¯Äܶ¨Àí¼´¿ÉÇóµÃÀ­Á¦×öµÄ¹¦£»Òà¿ÉÏÈÇó½âÀ­Á¦£¬È»ºó°´¹¦µÄ¶¨ÒåʽÇó½â£®

½â´ð ½â£º£¨1£©ÔÚ0-0.5sÄÚ£¬¸ù¾ÝͼÏó£¬A¡¢BϵͳµÄ¼ÓËÙ¶ÈΪ£º
${a_1}=\frac{v}{t}=\frac{2}{0.5}m/{s^2}=4m/{s^2}$£»
¶ÔA¡¢BÊÜÁ¦·ÖÎö£¬ÉèÉþ×Óµ¯Á¦ÎªT£¬ÄÇôÓÉÅ£¶ÙµÚ¶þ¶¨Âɿɵãº
m_Bg-T=m_Ba₁
T-m_Agsin¦È-¦Ìm_Agcos¦È=m_Aa₁£»
½âµÃ£º$¦Ì=\frac{{m}_{B}g-{m}_{A}gsin¦È-{m}_{A}{a}_{1}-{m}_{B}{a}_{1}}{{m}_{A}gcos¦È}=0.25$£»
£¨2£©ÔÚ0-0.5sÄÚA¼ÓËÙÏòÉÏ»¬¶¯µÄλÒÆΪ£º${x_1}=\frac{v^2}{{2{a_1}}}=0.5m$£»
BÂäµØºó£¬A¼ÌÐø¼õËÙÉÏÉý£®ÓÉÅ£¶ÙµÚ¶þ¶¨Âɿɵãºm_Agsin¦È+¦Ìm_Agcos¦È=m_Aa₂£¬
½âµÃ£º${a_2}=8m/{s^2}$£»
¹ÊA¼õËÙÏòÉÏ»¬¶¯µÄλÒÆΪ£º${x_2}=\frac{v^2}{{2{a_2}}}=0.25m$£»
ËùÒÔ£¬AÉÏ»¬µÄ×î´óλÒÆΪ£ºx=x₁+x₂=0.75m£»
£¨3£©A¼ÓËÙÉÏ»¬¹ý³ÌÖУ¬Ï¸Éþ¶ÔAµÄÀ­Á¦Îª£ºT=m_Agsin¦È+¦Ìm_Agcos¦È+m_Aa₁=24N
¹Ê»¬¶¯¹ý³ÌÖÐϸÏ߶ÔAµÄÀ­Á¦Ëù×öµÄ¹¦Îª£º$W=Ts=T¡Á\frac{1}{2}vt=24¡Á\frac{1}{2}¡Á2¡Á0.5J=12J$£»
»ò¶Ô¼ÓËÙÉÏÉý¹ý³ÌÓ¦Óö¯Äܶ¨Àí£¬¼´Îª£º$W-£¨{m_A}gsin¦È+¦Ì{m_A}gcos¦È£©{x_1}=\frac{1}{2}{m_A}{v^2}-0$
Ôò¿ÉµÃ£ºW=12J£»
´ð£º£¨1£©AÓëбÃæ¼äµÄ¶¯Ä¦²ÁÒòÊýΪ0.25£»
£¨2£©AÑØбÃæÏòÉÏ»¬¶¯µÄ×î´óλÒÆΪ0.75m£»
£¨3£©»¬¶¯¹ý³ÌÖÐϸÏ߶ÔAµÄÀ­Á¦Ëù×öµÄ¹¦Îª12J£®

µãÆÀ ÎïÌåµÄÔ˶¯ÎÊÌ⣬һ°ãÏȶÔÎïÌå½øÐÐÊÜÁ¦·ÖÎö£¬È»ºó¸ù¾ÝÅ£¶ÙµÚ¶þ¶¨ÂɺͶ¯Äܶ¨ÀíÇó½âËٶȡ¢¼ÓËٶȡ¢×ö¹¦µÈÎÊÌ⣬½ø¶øµÃµ½Ô˶¯Ê±¼äµÈºÍÔ˶¯¹ý³ÌÏà¹ØµÄÎïÀíÁ¿£®