Calculating Entropy Change in Niagara Falls Waterfall

Click For Summary
To calculate the increase in entropy per second at Niagara Falls, the relevant equation is S = Q/T, where Q represents the heat energy converted from potential energy as water falls. The water falls 50.0 m, and with a constant temperature of 20.0°C, the potential energy converts to kinetic energy and subsequently to heat energy. The participant initially struggled with the concept of heat change but realized that the energy conversion leads to an increase in entropy. The final solution involves calculating the heat energy based on the mass of water falling and its height. Understanding the relationship between potential energy and entropy change is crucial for solving this problem.
XianForce
Messages
16
Reaction score
0

Homework Statement


Every second at Niagara Falls, some 5.0 10^3 m3 of water falls a distance of 50.0 m. What is the increase in entropy per second due to the falling water? Assume that the mass of the surroundings is so great that its temperature and that of the water stay nearly constant at 20.0°C. Also assume a negligible amount of water evaporates.

Homework Equations



S = ∫ dQ/T

The Attempt at a Solution



Well, if I divided across by Δt, then I would have an equation set up for the quantity I need.

Temperature is constant, but since there is no real change in temperature or phase, is there any real change in heat? I'm not sure of where to go from here.

EDIT: Nevermind, I figured it out. Potential Energy converts to Kinetic Energy then to Heat Energy. Entropy is Q/T.
 
Last edited:
Physics news on Phys.org
so how do you solve this problem?
 

Thread 'Magnitude of buoyant force in fluids of different densities'

The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?
View full post »

Similar threads

Change in entropy of the surroundings in an irreversible process
  • · Replies 14 ·
Replies
14
Views
1K
Change in Entropy When Mixing Water at Different Temperatures
  • · Replies 5 ·
Replies
5
Views
1K
The Entropy Change of Melting Ice: Why is the Equation Written as ΔS = Q/T?
  • · Replies 4 ·
Replies
4
Views
2K
Ice cube in water: entropy calculation (Calorimetry)
  • · Replies 6 ·
Replies
6
Views
527
Entropy change for water in contact with a reservoir
  • · Replies 4 ·
Replies
4
Views
4K
Change in temperature for a system with entropy change
  • · Replies 4 ·
Replies
4
Views
2K
Entropy change for two masses of water mixed adiabatically
  • · Replies 1 ·
Replies
1
Views
2K
Entropy and the Helmholtz Free Energy of a Mass-Piston System
  • · Replies 8 ·
Replies
8
Views
2K
Entropy and the Laws of Thermodynamics
  • · Replies 3 ·
Replies
3
Views
2K
Entropy change and reversible/irreversible processes
  • · Replies 1 ·
Replies
1
Views
2K