Physics problems.A compound machine used to raise heavy boxes consists of a ramp and a pulley.The efficiency of pulling a 100-kg box up the ramp is 50%.If the efficiency of the pulley is 90%,what is the overall efficiency of the compound machine?

Where's Mike?He is working _____ physics A in;problem B out;problem C in；problems D on;problems some physics problems ___ the book are not difficult.A in B of 原因 There are some diffcult physics problems 改为单数句 哪里有Physics Principles And Problems整本中文翻译 I have lost my interested ( ) physics.I have lost my interested ( ) physics.A .in B .on C .at D .for 1、Last week they had some ( ) in solving the physics problem in the examination.A.difficulties B.problems C.trouble D.difficult2、--Why did John leave that position?--I hear that he ( ) a better job at IBM.A.is given B.was offered C.had been provi chemistry is the science of substances ___the science of energy .a and is physics b or is physics c and physics d or physics is 选什么 为什么 谢啦 单项选择 -Where's Mike? -He is working ( ) physics ( ) in the classroom. A.in；problemB.out；problemC.in；problemsD.on；problems I have a lot of problems____ physics A.for B.from C.with D.on I think physics ---- more difficult than math A.is B.are C.have D has my physics teacher said that light ____ faster than sound.a.travel b.travels c.traveled Who taught ______ physics last year?A your B yours C yourself D you I'm afraid that boy has some difficulty s--- the physics problems. Tom is weak in physics.He always feels _______ before he takes a physics test.Tom is weak in physics.He alwaysfeels _______ before he takes a physics test.A.interested B.comfortable C.nervous D.proud要有解析,不要只给答案 What difficult did you have______the problems?A.What difficult did you have______the problems?A.solved B.solving C.to solve William has( )great interest in( )physics.A,a;/ B,/;a C,/;the D,the;the选什么,为什么? 35、 He knows ____of physics, and still less of chemistry. A、few B、a few C、little D、a little AP SAT physcis B 和 physics CAP physics B 和physics C 有何区别,应该考C