Physics - Power

• Mar 5th 2008, 11:23 AM
vesperka
Physics - Power
Not even sure where to start with this one :\

Water flows over a section of Niagara Falls at
a rate of 1.4 x 10^6 kg/s and falls 59 m.
The acceleration of gravity is 9.8 m/s^2.
What is the power wasted by the waterfall?
Answer in units of W.
• Mar 5th 2008, 01:37 PM
JaneBennet
In one second, $1.4\times10^6\ \textrm{kg}$ of water passes through that particular section. The work done by gravity on this mass of water as it falls through $59\ \textrm{m}$ is $1.4\times10^6\times9.8\times59=8.0948\times10^8\ \textrm{J}$. This is the amount of energy “wasted” per second; hence the power wasted by the waterfall is $8.0948\times10^8\ \textrm{W}$.
• Mar 5th 2008, 03:38 PM
vesperka
Thanks man. I haven't worked with power before but I'm starting to see how the whole thinking process works now, thanks a bunch :D