1、S=3h=3*6m=18m,t=60S
v=S/t=18m/60s=0.3m/s
2、W有用=Gh=900N*6m=5400J
W总=W有用/η=5400/60%=9000J
P=W总/t=9000J/60s=150W
3、对动滑轮做的功就是额外功
W额=W总-W有用=9000J-5400J=3600J
W额=G动h
G动=W额/h=3600J/60m=60N
i j
1、S=3h=3*6m=18m,t=60S
v=S/t=18m/60s=0.3m/s
2、W有用=Gh=900N*6m=5400J
W总=W有用/η=5400/60%=9000J
P=W总/t=9000J/60s=150W
3、对动滑轮做的功就是额外功
W额=W总-W有用=9000J-5400J=3600J
W额=G动h
G动=W额/h=3600J/60m=60N
i j