八年级下册物理(电功率练习)

发布网友发布时间：2024-04-05 23:05

共3个回答

热心网友时间：2024-04-16 11:54

1. W = 40w * 30min = 40w * 1800s = 7200J
W = 40w * 30min = 0.04w * 0.5h = 0.02kw·h
2. 每天消耗 250w * 3h = 0.25kw *3h = 0.75kw·h
每月则 0.75kw·h * 30d = 22.5kw·h
3. 一节课40分钟，
总功率P=40W×15=0.04kW×15=0.6kW,
而t=40min=2/3h
W=Pt=0.6kW×2/3h=0.4kW.h
4、（1）：t=30min=1800s,W=0.6kW.h=2160000J,
P=W/t=2160000J/1800s=1200W
(2)、解：P=1200W, t=2min=120s
W=Pt=1200W×120s=144000J
5、解：W=120/3000=0.04kW.h=144000J, t=1min=60s
P=W/t=144000J/60s=2400W

热心网友时间：2024-04-16 11:52

1、解：P=40W=0.04kW , t=30min=0.5h,
W=Pt=0.04kW×0.5h=0.02kW.h
2、解：P=250W=0.25kW, t=3×30=90h,
W=Pt=0.25kW×90h=22.5kW.h
3、解：P=40W×15=0.04kW×15=0.6kW, t=40min=2/3h
W=Pt=0.6kW×2/3h=0.4kW.h
4、（1）、解：t=30min=1800s,W=0.6kW.h=2160000J,
P=W/t=2160000J/1800s=1200W
(2)、解：P=1200W, t=2min=120s
W=Pt=1200W×120s=144000J
5、解：W=120/3000=0.04kW.h=144000J, t=1min=60s
P=W/t=144000J/60s=2400W

热心网友时间：2024-04-16 11:47

(1)w=pt=40*1800=72000J 合0.02Kw,h