如图所示是某建筑工地用升降机提升大理石的滑轮组示意图．滑轮组通过固定架被固定住，滑轮组中的两个定滑
\u67d0\u5efa\u7b51\u5de5\u5730\u7528\u5347\u964d\u673a\u63d0\u5347\u5927\u7406\u77f3\u7684\u793a\u610f\u56fe\u5982\u56fe\u6240\u793a\u3002\u5347\u964d\u673a\u8d27\u7bb1\u7684\u91cd\u529b\u662f400N\uff0cg\u53d610N/kg\u3002\u4e0d\u8ba1\u6ed1\u8f6e\u548c\u94a2\u4e1d\u7ef3(1) (2) \uff083\uff09 (1) \u6bcf\u5757\u5927\u7406\u77f3\u91cd\uff1a \uff082\u5206\uff09(2) \u5347\u964d\u673a\u4e00\u6b21\u80fd\u63d0\u8d77\u7684\u5927\u7406\u77f3\u5757\u6570\uff1a \uff081\u5206\uff09(3) \u94a2\u4e1d\u7ef3\u7aef\u79fb\u52a8\u7684\u8ddd\u79bb\uff1a \uff081\u5206\uff09 \u628a\u8d27\u7269\u63d0\u534715 m\u505a\u7684\u529f\uff1a \uff081\u5206\uff09\u5347\u964d\u673a\u7684\u529f\u7387\uff1a \uff081\u5206\uff09\uff081\uff09\u5148\u7531m=\u03c1V\u8ba1\u7b97\u6bcf\u5757\u5927\u7406\u77f3\u7684\u8d28\u91cf\uff0c\u518d\u7531G=mg\u6c42\u51fa\u6bcf\u5757\u5927\u7406\u77f3\u7684\u91cd\u529b\uff1b\uff082\uff09\u7531\u56fe\u53ef\u77e5\u6709\u4e09\u6bb5\u94a2\u4e1d\u63d0\u7740\u8d27\u7bb1\uff0c\u5219\u8d27\u7bb1\u603b\u91cd\u662f\u94a2\u4e1d\u62c9\u529b\u76843\u500d\uff0c\u53bb\u6389\u8d27\u7bb1\u7684\u91cd\u529b\u5c31\u662f\u7816\u7684\u91cd\u529b\uff0c\u4e5f\u5c31\u80fd\u6c42\u51fa\u7816\u7684\u5757\u6570\uff1b\uff083\uff09\u94a2\u4e1d\u7ef3\u79fb\u52a8\u7684\u8ddd\u79bb\u662f\u8d27\u7bb1\u4e0a\u5347\u8ddd\u79bb\u76843\u500d\uff0c\u5229\u7528W=Fs\u6c42\u51fa\u94a2\u4e1d\u7ef3\u505a\u7684\u529f\uff0c\u518d\u5229\u7528 \u5f97\u94a2\u4e1d\u7ef3\u7684\u62c9\u529b\u7684\u529f\u7387\uff0e\u8be5\u9898\u6d89\u53ca\u5230\u5bc6\u5ea6\u3001\u91cd\u529b\u3001\u529f\u3001\u529f\u7387\u3001\u6ed1\u8f6e\u7ec4\u7b49\u7684\u8ba1\u7b97\uff0c\u662f\u4e00\u7efc\u5408\u6027\u8f83\u5f3a\u7684\u9898\uff0c\u5728\u8ba1\u7b97\u8fc7\u7a0b\u4e2d\u8981\u6ce8\u610f\u5404\u4e2a\u7269\u7406\u91cf\u4e4b\u95f4\u7684\u5173\u7cfb\uff0c\u8003\u67e5\u4e86\u5b66\u751f\u7684\u7efc\u5408\u5e94\u7528\u80fd\u529b\uff0c\u5c5e\u4e8e\u96be\u9898\uff0e\u3010\u8003\u70b9\u3011\u5bc6\u5ea6\u516c\u5f0f\u7684\u5e94\u7528\uff1b\u6ed1\u8f6e\u7ec4\u7ef3\u5b50\u62c9\u529b\u7684\u8ba1\u7b97\uff1b\u91cd\u529b\u7684\u8ba1\u7b97\uff1b\u529f\u7387\u7684\u8ba1\u7b97\uff0e
\uff081\uff09\u7531\u56fe\u793a\u53ef\u77e5\uff0c\u6ed1\u8f6e\u7ec4\u627f\u91cd\u7ef3\u5b50\u7684\u80a1\u6570n=3\uff0c\u5347\u964d\u673a\u4e00\u6b21\u80fd\u591f\u63d0\u8d77\u7684\u603b\u91cd\uff1aG\u603b=nF\u6700\u5927=3\u00d72000N=6000N\uff0c\u5347\u964d\u673a\u4e00\u6b21\u80fd\u63d0\u8d77\u7684\u5927\u7406\u77f3\u7684\u603b\u91cd\uff1aG\u77f3=G\u603b-G0=6000N-400N=5600N\uff1b\uff082\uff09\u94a2\u4e1d\u7ef3\u7aef\u79fb\u52a8\u7684\u8ddd\u79bb\uff1as=nh=3\u00d715m=45m\u628a\u8d27\u7269\u63d0\u534715m\u62c9\u529b\u505a\u7684\u529f\uff1aW=Fs=2000N\u00d745m=9\u00d7104J\u5347\u964d\u673a\u7684\u529f\u7387\u4e3aP=Wt=9\u00d7104J60s=1500W\uff0e\u7b54\uff1a\uff081\uff09\u8be5\u5347\u964d\u673a\u4e00\u6b21\u6700\u591a\u80fd\u5300\u901f\u63d0\u53475600N\u7684\u5927\u7406\u77f3\uff1b\uff083\uff09\u5347\u964d\u673a\u7684\u529f\u7387\u4e3a1500W\uff0e
（1）由ρ=
| m |
| V |
m=ρV=2.8×103kg/m3×1.0×10-2m3=28kg
每块大理石重：G=mg=28kg×10N/kg=280N；
升降机一次能够提起的总重为G总=3×F最大=3×2000N=6000N
升降机一次能提起的大理石的总重为G石=G总-G0=6000N-300N=5700N
升降机一次能提起的大理石的块数为n=
| G石 |
| G |
| 5700N |
| 280N |
（2）提升15块大理石的过程中，钢丝绳端移动的距离：s=3h=3×15m=45m
F=
| 1 |
| 3 |
| 1 |
| 3 |
（3）把货物提升15m拉力做的功：W=Fs=1500N×45m=6.75×104J
升降机的功率为P=
| W |
| t |
| 6.75×104J |
| 60s |
（4）W有用=Gh=15×280N×15m=6.3×104J，
η=
| W有用 |
| W总 |
| 6.3×104J |
| 6.75×104J |
故选C．
绛旓細a1=v?0t1=5?02 m/s2=2.5 m/s25锝8 s鍐呭姞閫熷害涓篴2=0?vt2=0?53 m/s2=-53 m/s2锛庢墍浠1涓巃2澶у皬涔嬫瘮涓3锛2锛庣瓟锛氾紙1锛鍗囬檷鏈鍦0锝2 s鍐呭仛鍔犻熷害涓嶅彉鐨勫姞閫熻繍鍔紝2锝5 s鍐呭寑閫熻繍鍔紝5锝8 s鍐呭仛鍔犻熷害涓嶅彉鐨勫噺閫熻繍鍔紟锛2锛0锝2s涓5s锝8s鍐呯殑鍔犻熷害澶у皬涔嬫瘮鏄3锛2锛
绛旓細72.5m 璇曢鍒嗘瀽锛氬寑鍔犻熶笂鍗囪繃绋嬶細鍔犻熷害 锛屾墍浠ュ彂鐢熺殑浣嶇Щ涓 鍖閫熻繃绋嬶細 鍑忛熻繃绋嬶細 锛屽彂鐢熺殑浣嶇Щ涓 鎵浠ヨ繃绋嬩腑鐨勬讳綅绉讳负 鐐硅瘎锛氭绫诲瀷棰樹腑鐨勬暟鎹瘮杈冨锛岋紝鍏抽敭鏄垎娓呮姣忎釜鏁版嵁琛ㄧず鐨勫惈涔夛紝鐒跺悗鏍规嵁淇℃伅閫夋嫨鍏紡璁＄畻
绛旓細鍔熺巼P=鍔焀/鍋氬姛鏃堕棿s銆傚姛W=鍋氬姛鐨勫姏F脳鍋氬姛鐨勮窛绂籐 1.2t=12000kg 鎵浠ュ姏F=12000kg脳9.8N/kg=117600N路m銆2妤煎埌5妤硷紝姣忓眰3绫筹紝涓鍏变笂鍗囦簡9绫炽俉=F脳L=117600脳锛5-2锛壝3=1058400J锛堢劍灏旓級鎵浠=W/S=1058400梅10=105840W鐡=105.84kW锛堝崈鐡︼級鍗囬檷鏈鍔熺巼鏄105.84kW锛堝崈鐡︼級搴旇鏄...
绛旓細鍗囬檷鏈鎬婚噸锛欸=mg锛1.2脳1000kg脳10N/kg锛12000N 鍋氬姛锛歐锛滸h锛12000N脳锛3脳3m锛夛紳108000J 鍔熺巼锛歅锛漌/t锛108000J/10s锛10800W 鍗筹細10.8kW銆
绛旓細鍗囬檷鏈鐨勭浣撹繛鍚岃揣鐗╃殑鎬婚噸鍔涳細G=mg=1.2脳103kg脳10N/kg=1.2脳104N锛庝粠妤肩殑2灞備笂鍗囧埌5灞傜殑楂樺害涓猴細h=3m脳3=9m锛屽垯鍗囬檷鏈鸿嚦灏戝仛鐨勫姛涓篧=Gh=1.2脳104N脳9m=1.08脳105J锛涘崌闄嶆満鐨勫姛鐜囪嚦灏戜负锛歅=Wt=1.08脳105J10s=1.08脳104W锛庢晠閫夛細B锛
绛旓細W=F2s=2000N脳24m=48000J锛岄挗涓濈怀鑷敱绔媺鍔涚殑鍔熺巼锛歅=Wt=48000J30s=1600W锛涳紙3锛夋湁鐢ㄥ姛锛歐鏈=Gh=6000N脳6m=36000J锛屾诲姛锛歐鎬=P杈撳叆t=2000W脳30s=60000J锛岃瑁呯疆鐨勬晥鐜囷細畏=W鏈塛鎬幻100%=36000J60000J脳100%=60%锛庣瓟锛氾紙1锛夊湪鍖閫熸彁鍗囦腑锛岃揣鐗╁璐у帰搴曢儴鐨勫帇寮烘槸3000Pa锛涳紙...
绛旓細鍥炬槸鎻愬崌璐х墿鐨勬煇鍗囬檷鏈虹ず鎰忓浘銆傝揣鍘㈠唴鎵瑁呰揣鐗╃殑閲嶅姏鏄6000N,璐у帰鐨勯噸鍔涙槸2000N銆傝嫢涓嶈閽笣缁冲拰鍔ㄦ粦杞殑閲嶅姏,涓嶈鎽╂摝(1)鍦ㄥ寑閫熸彁鍗囦腑,婊戣疆缁勭殑鏈烘鏁堢巼鏄灏?2)鑻ュ崌闄嶆満鍦... 鍥炬槸鎻愬崌璐х墿鐨鏌愬崌闄嶆満绀烘剰鍥俱傝揣鍘㈠唴鎵瑁呰揣鐗╃殑閲嶅姏鏄6000 N,璐у帰鐨勯噸鍔涙槸2000 N銆傝嫢涓嶈閽笣缁冲拰鍔ㄦ粦杞殑閲嶅姏,涓嶈...
绛旓細F=(G1+G2)/4=锛6000+2000锛/4=2000N P=W/t=Fs/t=2000*6*4/30=1600w
绛旓細鈶0-2s鏄寑鍔犻熼樁娈碉紝鍔犻熷害a=5/2(m/s²)2-5s涓哄寑閫熼樁娈碉紝閫熷害v=5(m/s)5-8s涓哄寑鍑忛熼樁娈碉紝鍔犻熷害a'=-5/3(m/s²)鈶:a'=5/2:5/3=3:2
绛旓細寤虹瓚宸ュ湴涓婄殑鍗囬檷鏈鏄部鐩寸嚎鏂瑰悜鐨勪粈涔堣繍鍔 A銆佺敱鍥惧彲鐭ワ紝鍗囬檷鏈轰竴鐩村湪鏃堕棿杞存鏂瑰悜杩愬姩锛屾墍浠ラ噸鐗╀竴鐩村悜涓婅繍鍔紝鏁匒閿欒锛嶣銆侀熷害鍥捐薄鐨勬枩鐜囩瓑浜庣墿浣撶殑鍔犻熷害澶у皬锛岀敱鍥惧彲鐭ワ紝閲嶇墿鍏堝仛鍖鍔犻熺洿绾胯繍鍔紝鍔犻熷害涓嶅彉锛屽悗鍋氬寑鍑忛熺洿绾胯繍鍔紝鍔犻熷害涔熶繚鎸佷笉鍙橈紝浣嗕袱涓繃绋嬪姞閫熷害涓嶅悓锛庢晠B閿欒锛孋銆佺敱鍥...
