图是某建筑工地提升建材所用的升降机示意图。建材的重力是6300N,建材与货箱水平底面的接触面积是1.2m 2 某建筑工地用升降机提升实心砖的示意图如图所示.升降机货箱的重...
\uff082010?\u5927\u8fde\uff09\u67d0\u5efa\u7b51\u5de5\u5730\u7528\u5347\u964d\u673a\u63d0\u5347\u5b9e\u5fc3\u7816\u7684\u793a\u610f\u56fe\u5982\u56fe\u6240\u793a\uff0e\u5347\u964d\u673a\u8d27\u7bb1\u7684\u91cd\u529b\u662f300N\uff0cg\u53d610N/kg\uff0e\u4e0d\u8ba1\uff081\uff09\u7816\u7684\u5bc6\u5ea6\uff1a\u03c1=2\u00d7103kg/m3\u6bcf\u5757\u8f6c\u7684\u4f53\u79ef\uff1aV=1.5\u00d710-3m3\u6bcf\u5757\u7816\u7684\u8d28\u91cf\uff1am=\u03c1V=2\u00d7103kg/m3\u00d71.5\u00d710-3m3=3kg\u6bcf\u5757\u7816\u7684\u91cd\u529b\uff1aG=mg=3kg\u00d710N/kg=30N\uff1b\uff082\uff09\u8d27\u7bb1\u7684\u603b\u91cd\uff1aG\u603b=3\u00d7F\u62c9=3\u00d72100N=6300N\u7816\u7684\u603b\u91cd\uff1aG\u7816=G\u603b-G\u7bb1=6300N-300N=6000N\u7816\u7684\u5757\u6570\u662f\uff1a6000N30N=200\u5757\uff1b\uff083\uff09\u94a2\u4e1d\u7ef3\u79fb\u52a8\u7684\u8ddd\u79bb\uff1aL=10m\u00d73=30m\u94a2\u4e1d\u7ef3\u7684\u62c9\u529b\uff1aF\u62c9=2000N\u62c9\u529b\u505a\u7684\u529f\uff1aW=F\u62c9L=2000N\u00d730m=60000J\u62c9\u529b\u505a\u7684\u529f\u7387\uff1aP=Wt=60000J50s=1200W\uff1b\u7b54\uff1a\uff081\uff09\u5757\u7816\u7684\u91cd\u529b\u662f\uff1a30N\uff1b\uff082\uff09\u5347\u964d\u673a\u4e00\u6b21\u6700\u591a\u80fd\u5300\u901f\u63d0\u5347200\u5757\uff1b\uff083\uff09\u94a2\u4e1d\u7ef3\u7684\u62c9\u529b\u7684\u529f\u7387\u662f\uff1a1200W\uff0e
\u89e3\uff1a\uff081\uff09\u7816\u7684\u5bc6\u5ea6\uff1a\u03c1=2\u00d710 3 kg/m 3 \u6bcf\u5757\u8f6c\u7684\u4f53\u79ef\uff1aV=1.5\u00d710 \ufe633 m 3 \u6bcf\u5757\u7816\u7684\u8d28\u91cf\uff1am=\u03c1V=2\u00d710 3 kg/m 3 \u00d71.5\u00d710 \ufe633 m 3 =3kg \u6bcf\u5757\u7816\u7684\u91cd\u529b\uff1aG=mg=3kg\u00d710N/kg=30N\uff082\uff09\u8d27\u7bb1\u7684\u603b\u91cd\uff1aG \u603b =3\u00d7F \u62c9 =3\u00d72100N=6300N\u7816\u7684\u603b\u91cd\uff1aG \u7816 =G \u603b \ufe63G \u7bb1 =6300N\ufe63300N=6000N \u7816\u7684\u5757\u6570\u662f\uff1a =200\u5757\uff083\uff09\u94a2\u4e1d\u7ef3\u79fb\u52a8\u7684\u8ddd\u79bb\uff1aL=10m\u00d73=30m\u94a2\u4e1d\u7ef3\u7684\u62c9\u529b\uff1aF \u62c9 =2000N \u62c9\u529b\u505a\u7684\u529f\uff1aW=F \u62c9 L=2000N\u00d730m=60000J \u62c9\u529b\u505a\u7684\u529f\u7387\uff1aP= = =1200W
解:(1)p=F/S=G/S =6300N/1.2m 2 =5250Pa (2分) (2)由P=W/t可得,F所做的功W F =Pt=1800W×60s=1.08×10 7 J(2分) (3)W=FS可得 W 有 =Gh=6300N×12m=7.56×10 4 J (1分) W 总 = W F =1.08×10 7 J η= W 有 / W 总 = W 有 /W F ="7.56×104J/1.08×107" J=70% (2分) 答:(1)建材对货箱水平底面的压强是5250Pa。 (2)拉力F所做的功是1.08×107 J。 (3)该滑轮组提升这些建材的机械效率是70% 。 绛旓細锛2锛夋媺鍔汧鎵鍋氱殑鍔熸槸1.08脳107 J銆傦紙3锛夎婊戣疆缁鎻愬崌杩欎簺寤烘潗鐨鏈烘鏁堢巼鏄70% 銆 锛1锛夋姹傚帇寮哄簲璇ョ煡閬撳帇鍔涗笌鍙楀姏闈㈢Н锛屽帇鍔涚殑澶у皬灏辩瓑浜庡缓鏉愰噸鍔涚殑澶у皬锛屽彈鍔涢潰绉繕鏄凡鐭ョ殑锛屾晠鍘嬪己鍙眰锛涳紙2锛夋眰鎷夊姏鐨勫姛锛岀敱浜庨涓凡鐭ュ姛鐜囧拰鏃堕棿锛岀洿鎺ョ敤鍏紡姹傚嚭鍗冲彲锛涳紙3锛夋姹傛満姊版晥鐜囷紝搴旇鐭ラ亾鏈夌敤... 绛旓細瑙o細锛1锛鎻愬崌寤烘潗鏃舵墍鍋氱殑鏈夌敤鍔焀 鏈夌敤 =Gh=900N脳10m=9000J锛屼笂鍗囬熷害v 鐗 = = =0.4m/s鎵鐢鏃堕棿t= = =25s锛屾湁鐢ㄥ姛鐜嘝 鏈夌敤 = = =360W銆傦紙2锛変汉鐨勬媺鍔汧= = =500N锛岀怀瀛愯嚜鐢辩绉诲姩鐨勮窛绂籗 缁 =2S 鐗 =2脳10m=20m锛屼汉鎵鍋氱殑鎬诲姛W 鎬 =FS 缁 =500N脳20m=... 绛旓細锛1锛夊伐浜哄仛鐨勬湁鐢ㄥ姛锛屼粈涔堝彨鏈夌敤鍔燂紵灏辨槸鐪熸鐢ㄥ埌鐐瑰瓙涓婄殑鍔!閭d箞鍥句腑鐨勫伐浜哄彧鏈変竴涓洰鐨勶紝灏辨槸鎶婂缓鏉愭彁鍗囧埌6m鐨勯珮绌猴紝涔熷氨鏄锛屼粬鐪熸璧蜂綔鐢ㄧ殑鍔熷氨鏄缓鏉愭彁鍗闇瑕佺殑鍔燂紝鎬诲叡鏄 230N 脳 6m =1380 J 锛2锛 宸ヤ汉鐨勬诲姛锛屽氨鏄粬鎬诲叡鍋氱殑鍔燂紝涓嶇鏈夌敤娌℃湁閮界畻涓婏紙涓嶅悓浜庢湁鐢ㄥ姛锛夈傛棰樺彲... 绛旓細瑙g瓟锛氬凡鐭ワ細寤烘潗閲嶄负G=400N锛鎻愬崌楂樺害h=2m锛屾媺鍔涗负F=250N锛屾椂闂翠负t=20s锛岄噸鐗╅噸G鈥=900N锛庢眰锛氾紙1锛夊伐浜哄仛鐨勬湁鐢ㄥ姛W鏈夌敤=锛燂紱锛2锛夊伐浜哄仛鍔熺殑鍔熺巼P=锛燂紱锛3锛夎瑁呯疆鐨勬満姊版晥鐜囄=锛燂紱锛4锛夊伐浜哄仛鐨勬诲姛W鎬=锛熻В锛氾紙1锛夊伐浜哄仛鐨勬湁鐢ㄥ姛锛歐鏈=Gh=400N脳2m=800J锛涳紙2锛夌怀瀛愮Щ鍔ㄨ窛绂伙細... 绛旓細澧炲ぇ鎻愬崌鐨鐗╀綋閲嶅姏鎴栧湪鎻愬崌鐨勯噸鐗╀笉鍙樻椂鍑忓皬棰濆鍔燂紟鎵浠ワ紝鍦ㄨ鍙寖鍥村唴姣忔澶氳皟杩愪竴浜寤烘潗锛堟垨鍑忚交鍔ㄦ粦杞殑鑷噸銆佹垨鍦ㄦ粦杞浆杞村鍔犳鼎婊戞补锛夛紟绛旓細锛1锛夊伐浜哄仛鐨勬湁鐢ㄥ姛涓1380J锛涳紙2锛夋杩囩▼涓瑁呯疆鐨勬満姊版晥鐜囦负92%锛涳紙3锛夊伐浜哄仛鍔熺殑鍔熺巼涓75W锛涳紙4锛夊湪璁稿彲鑼冨洿鍐呮瘡娆″璋冭繍涓浜涘缓鏉愶紙鎴栧噺杞诲姩... 绛旓細绗簩娆鎻愬崌閲嶇墿鏃剁殑鎷夊姏锛欶鈥=12锛圙鈥+G鍔級=12脳锛300N+20N锛=160N锛屾湁鐢ㄥ姛锛歐鏈夌敤鈥=G鈥瞙=300N脳10m=3000J锛屽伐浜哄仛鐨勬诲姛锛歐鎬烩=F鈥瞫=160N脳20m=3200J锛屾粦杞粍鐨勬満姊版晥鐜囷細畏=W鏈夌敤鈥瞁鎬烩裁100%=3000J3200J脳100%=93.75%锛庣瓟锛氾紙1锛夎瑁呯疆鐨勬満姊版晥鐜囦负92%锛涳紙2锛夊伐浜哄仛鍔... 绛旓細宸茬煡锛欸=500N锛孎=300N锛宧=6m锛宼=20s锛庢眰锛氾紙1锛夊伐浜哄仛鐨勬湁鐢ㄥ姛锛涳紙2锛夊伐浜哄仛鍔熺殑鍔熺巼锛涳紙3锛夋杩囩▼涓瑁呯疆鐨勬満姊版晥鐜囷紱锛4锛夊鏋滅敤杩欎釜婊戣疆缁勫寑閫熸彁璧400N鐨勯噸鐗╋紝闇瑕佺敤澶氬ぇ鐨勬媺鍔涜В锛氱敱鍥剧ず鍙煡锛屾粦杞粍缁冲瓙鐨勬湁鏁堣偂鏁皀=2锛涳紙1锛夊伐浜哄仛鐨勬湁鐢ㄥ姛锛歐鏈=Gh=500N脳6m=3000J锛涳紙2锛夊伐浜... 绛旓細锛1锛夊伐浜哄仛鐨勬诲姛锛歐鎬=Fs=Fnh=125N脳2脳6m=1500J锛涘伐浜哄仛鍔熺殑鍔熺巼锛歅=Wt=1500J10s=150W锛涳紙2锛夊伐浜哄仛鐨勬湁鐢ㄥ姛锛歐鏈=Gh=200N脳6m=1200J锛涙杩囩▼涓瑁呯疆鐨勬満姊版晥鐜囷細畏=W鏈塛鎬幻100%=1200J1500J脳100%=80%锛涳紙3锛夋牴鎹=W鏈塛鎬=GhGh+G鍔╤=GG+G鍔ㄥ彲鐭ワ細鎻愰珮鏈烘鏁堢巼鍙互鍦ㄤ繚鎸... 绛旓細锛1锛夊伐浜哄仛鐨勬湁鐢ㄥ姛锛歐鏈=Gh=200N脳6m=1200J锛涳紙2锛夌敱鍥惧彲鐭ワ紝n=2锛屽垯缁崇绉诲姩鐨勮窛绂伙細s=nh=2脳6m=12m锛屽伐浜哄仛鐨勬诲姛锛歐鎬=Fs=125N脳12m=1500J锛涳紙3锛夋杩囩▼涓瑁呯疆鐨勬満姊版晥鐜囷細畏=W鏈塛鎬幻100%=1200J1500J脳100%=80%锛涳紙4锛夊伐浜哄仛鍔熺殑鍔熺巼锛歅=W鎬籺=1500J10s=150W锛庣瓟锛氾紙1... 绛旓細1) F=230脳6=1380j 2锛塅锛堟伙級=125脳12=1500j 3锛壩=1380梅1500=92锛 4锛墂=1500梅20=750w 本站交流只代表网友个人观点,与本站立场无关 |