Question

11£®¹þ¶û±õµÚ24½ìÊÀ½ç´óѧÉú¶¬ÔË»áij»¬Ñ©µÀΪÇúÏß¹ìµÀ£¬»¬Ñ©µÀ³¤s=2.5¡Á10³m£¬ÊúÖ±¸ß¶Èh=720m£¬Ô˶¯Ô±´Ó¸Ã»¬µÀ¶¥¶ËÓɾ²Ö¹¿ªÊ¼»¬Ï£¬¾­t=200sµ½´ï»¬Ñ©µÀµ×¶ËʱËÙ¶Èv=30m/s£¬È˺ͻ¬Ñ©°åµÄ×ÜÖÊÁ¿m=80kg£¬gÈ¡10m/s²£¬ÇóÈ˺ͻ¬Ñ©°å
£¨1£©µ½´ïµ×¶ËʱµÄ¶¯ÄÜ
£¨2£©ÔÚ»¬¶¯¹ý³ÌÖÐÖØÁ¦×ö¹¦µÄ¹¦ÂÊ
£¨3£©ÔÚ»¬¶¯¹ý³ÌÖп˷þ×èÁ¦×öµÄ¹¦£®

Answer 1

·ÖÎö £¨1£©¸ù¾Ý¶¯Äܵıí´ïʽÇó³öÈ˺ͻ¬Ñ©°åµ½´ïµ×¶ËµÄ¶¯ÄÜ£»
£¨2£©¸ù¾ÝϽµµÄ¸ß¶ÈÇó³öÖØÁ¦×ö¹¦µÄ´óС£¬´Ó¶ø½áºÏƽ¾ù¹¦ÂʵĹ«Ê½Çó³öÖØÁ¦×ö¹¦µÄ¹¦ÂÊ£»
£¨3£©¸ù¾Ý¶¯Äܶ¨Àí£¬Çó³öÔÚ»¬¶¯¹ý³ÌÖп˷þ×èÁ¦×ö¹¦µÄ´óС£®

½â´ð ½â£º£¨1£©´ïµ½µ×¶ËµÄ¶¯ÄÜ£º${E}_{k}=\frac{1}{2}m{v}^{2}=\frac{1}{2}¡Á80¡Á3{0}^{2}=3.6¡Á1{0}^{4}J$£»
£¨2£©ÔÚ»¬¶¯¹ý³ÌÖУ¬ÖØÁ¦×ö¹¦£º
W_G=mgh=800¡Á720J=576000J£¬
ÔòÖØÁ¦µÄ¹¦ÂÊΪ£º
P=$\frac{{W}_{G}}{t}$=$\frac{576000}{200}=2880W$£®
£¨3£©¸ù¾Ý¶¯Äܶ¨ÀíµÃ£º
mgh-${W}_{f}=\frac{1}{2}m{v}^{2}$-0
´úÈëÊý¾Ý½âµÃ£ºWf=5.4¡Á105J£®
´ð£º£¨1£©µ½´ïµ×¶ËʱµÄ¶¯ÄÜΪ36000J£»
£¨2£©ÔÚ»¬¶¯¹ý³ÌÖÐÖØÁ¦×ö¹¦µÄ¹¦ÂÊΪ2880W£»
£¨3£©ÔÚ»¬¶¯¹ý³ÌÖп˷þ×èÁ¦×öµÄ¹¦Îª5.4¡Á10⁵J£®

µãÆÀ ±¾Ì⿼²éÁ˶¯ÄÜ¡¢¹¦ÂÊ¡¢¶¯Äܶ¨ÀíµÄ»ù±¾ÔËÓ㬱Ƚϼòµ¥£¬¶ÔÓÚ¹¦ÂÊ£¬ÒªÇø·ÖÇó½âµÄÊÇƽ¾ù¹¦ÂÊ»¹ÊÇ˲ʱ¹¦ÂÊ£®