(物理)初中物理简单机械专项检测试题及答案 - 百度文库 ر

𰸡B ⡿

֪õĻͬͬĸ߶ȣغĦ˷ĹǶ⹦W=Gh֪AB⹦ͬĦӰ죬ĻеЧʣ=

WWW?W=

WУ⹦ͬAʱ

ĻеЧʽϴAùϴ߶һAأAõϴ󣬹ACDBȷ

9ڻеЧʵ⣬˵ȷǣ AùԽ࣬еЧһԽ һԽ

CʡԽĻееЧһԽ СеЧһԽ 𰸡D ⡿

A࣬ùһ࣬ùռܹıһߣԻеЧʲһߣABùռܹı뵥λʱ޹أBCʡĻеĻеЧƫͣCD⹦ܹռԽС˵ùܹռıԽ󣬻еЧʾԽߣDȷѡD 㾦

ܹù+⹦ùܹıֵлеЧʣɻеЧʵĶ֪еЧʵĸߵֻùܹռıйأ١ʴС޹أ

D⹦ܹռԽBλʱԽ࣬еЧ

10ʦͼʾĻ飬Ϊ800Nﻺֱ3m˶FΪ500NغͻתᴦĦ

AɶƶľΪ9m CͨùΪ1500J 𰸡B

BֵΪ200N DĻеЧΪ53.3%

ͼ֪2ӳеͶֵأn=2ֱ3mɶƶľΪs=nh=23m=6mA ˹УùΪW=Gh=800N3m=2400JC ܹΪW=Fs=500N6m=3000J

⹦ΪW=W-W=3000J-2400J=600JغͻתᴦĦ⹦Ϊ˷ĹW=GhֵG=W/h=600J/3m=200NBȷΪ𰸣 ĻеЧ

D

㣺ĻеЧ ù ⹦

11Ϊ60kgĹͼʾĻͻ¥֪1minڽ6mڸΪ400NĻеЧı仯ͼʾеĦؾƣ˵ȷ

AڸϵĹΪ400W BֵΪ200N C˶ӵΪ1000N DûеЧΪ83.3% 𰸡B

1ͼ֪n=3ƶľs?nh W?Fs Ĺ

P?WĹʣ t2ͼҿ֪G=300NʱĻеЧʦ=60%

??WW=GhGhG??еĦغԲƣFsF3h3F1F?G?Gݴ󶯻

33ùֱɶͻʱӵڹ˵ 4F?G?GأеЧ

13??WGhG?? . W?G?G?h?G?G?⡿

1ͼ֪n=3ƶľ룺s?nh?3?6m?18m ĹW?Fs?400N?18m?7200J ĹʣP?W7200J??120WA t60s2ͼҿ֪G=300NʱĻеЧʦ=60% ??WW=GhGhGG300N500N??F????167N ɵã

3?3?60?sF3h3F1?G?G? 3еĦغԲƣF?ԣG?nF?G?3?500N?200N?300N Bȷ 33ùֱɶͻʱӵ

F?G?mg?60kg?10N/kg?600N C

4F?1G?G?ɵãأ?3G?nF?G?3?600N?200N?1600N

еĦؾƣеЧʣ

??

WGhG1600N????100%?88.9%DW?G?G?h?G?G?1600N?200NѡB

12ϵĹӿбˮƽϱƽ⣮ĸͼУȷʾϹޣϣʾͼǣ

A B

C D

𰸡A ⡿

ķʼֱ£CD

⣬ϵĹӿбˮƽϱƽ⣬ݸܸ˵ƽֻ֪߾֧ʱӲŻᱣƽ⣬AȷB ѡA 㾦

ؼǸݸܸ˵ƽ⵱һ֧ͨʱΪ㣬Ըܸ𲻵κãԭƽĸܸ˻Ȼƽ⣮

13ͰƽʱͰǹرղʹɢζʹʱýŲ̤壬ͰǿͰĽṹʾͼȷ

AͰֻһܸãΪʡܸ BͰֻһܸãΪܸ CͰܸãöʡܸ

DͰܸãһʡܸˣһǷܸ 𰸡D

ͼеͰܸˣDEFΪһܸˣ۴ʡܸˣABCΪһܸˣСڷܸˣʴѡD

㾦⿼ܸ˵ķ࣬ѵδеĹгܸˣⷽжʡܸʱӶۺ۵ĴС֣