Phy 練習中2條諗唔通- - F4

6.打中文ok??唔ok都要ok =v="
咁speed係m/s啦...即係每秒移動幾快啦...
而Power又係指每秒產生ge energy...
兩者ge單位都係xx per 1s..就可以mix埋黎計..
p=power...e=energy...t=time...每秒都係30w..即係每秒provide30J
P=E/t
E=30J per s
30=(1/2)mv^2
60=65v^2
v=0.960769
v=0.961ms^-1
his maximum speed of climbing up the rock surfaces is 0.961ms^-1
8.呢個ge work done係垂直..即係mgh
the energy is needed for raised at 2ms-1...
P=E/t
15x1000=mgh per s/t(per s)
15000w=m x10x2
m=750kg
the maximum number of people :(750-120)/70=9
so the maximum number of people who can be raised at 2ms^-1 is 9 people
有唔明再問~

2008-04-12 23:11:42 補充：
too easy 只不過我估唔到佢垂直咁爬 =口=
P=E/t
30=mgh/(per s)
30=650h
h=0.0462m per s
so the velocity 係0.0462ms^-1...垂直向上...
我見到rock surfaces仲以為佢打斜...甚至打橫..即係bb仔咁爬..
sorry呀 ^^"

2008-04-12 23:29:36 補充：
呀...原來物理愛好者—R 已經答咗..非常感謝你的幫忙~

-0-我知道了
P=E/t
30=work done by muscles /time
30=Gain in PE /time
30=(65)(10)(h)/time
v=0.0462 ms-1

這裡E=30J per s,應是E=30Js

HEYHEY!!!第6條既答案係 0.0462ms-1 bo,我一開始都係用你個方法計...但都係計你依個答案-0-