Question

ÈçͼËùʾ£¬Ë®Æ½×ÀÃæÀëµØÃæ¸ßh=1.25m£®Ð¡Îï¿éA¾²Ö¹ÔÚ×ÀÃæÉÏ£¬¾àÓÒ±ßÔµl=1m£¬Ð¡Îï¿éB´Ó×ÀÃæµÄ×ó±ßÔµÏòAÔ˶¯£¬²¢ÓëÖ®·¢ÉúÕýÅö£¨Åöײʱ¼ä¼«¶Ì£©£®ÅöºóA´Ó×ÀÃæµÄÓÒ±ßÔµÒÔ´¹Ö±±ßÔµµÄËٶȷɳö£¬ÆäÂäµØµã¾à×ÀÃæÓÒ±ßÔµµÄˮƽ¾àÀës=0.75m£¬B¸ÕºÃµ½´ï×ÀÃæÓÒ±ßÔµ£®AºÍBÖÊÁ¿¾ùΪm=0.1kg£¬Óë×ÀÃæ¼äµÄ¶¯Ä¦²ÁÒòÊý¾ùΪ¦Ì=0.2£®ÖØÁ¦¼ÓËÙ¶ÈΪg=10m/s²£®ÊÔÇó£º
£¨1£©Ð¡Îï¿éA´Ó×ÀÃæ±ßÔµ·É³öʱµÄËٶȴóС£®
£¨2£©Ð¡Îï¿éBÓëAÅöײ¹ý³ÌÖÐBÓëA×é³ÉµÄϵͳËðʧµÄ»úеÄÜ£®

Answer 1

£¨1£©Îï¿éA×öƽÅ×Ô˶¯µÄʱ¼ät=

2h g

=0.5s
´Ó×ÀÃæ±ßÔµ·É³öµÄËÙ¶ÈΪv=

s

t

=1.5m/s
£¨2£©ÅöײǰAµÄËÙ¶ÈΪv₀£¬ÅöײºóAµÄËÙ¶ÈΪv₁£¬BµÄËÙ¶ÈΪv₂£¬
¸ù¾Ý¶¯Äܶ¨ÀíÓУº-¦Ìmgl=

1

2

mv2-

1

2

mv12£¬-¦Ìmgl=0-

1

2

mv22
´øÈëÊý¾Ý½âµÃ£ºv₁=2.5m/s£¬v₂=2m/s
¸ù¾Ý¶¯Á¿ÊغãµÃ£º
mv₀=mv₁+mv₂
½âµÃ£ºv₀=4.5m/s
ÔòÅöºóËðʧµÄ»úеÄÜΪ¡÷E=

1

2

mv02-

1

2

mv12-

1

2

mv22=0.5J
´ð£º£¨1£©Ð¡Îï¿éA´Ó×ÀÃæ±ßÔµ·É³öʱµÄËٶȴóСΪ1.5m/s£®
£¨2£©Ð¡Îï¿éBÓëAÅöײ¹ý³ÌÖÐBÓëA×é³ÉµÄϵͳËðʧµÄ»úеÄÜΪ0.5J£®