Question

When n = energy efficiency and Pin = energy input and Pout = energy output, how can you mathematically represent the correct relationship between the energy you put in something and the energy you get out?
A. n = P out * P in
B. n = P out / P in
C. n = P out - P in

Answer 1

If a machine/process is perfectly energy efficient, then \( \nu = 1 \). That being the case, which is the only definition that works?

Answer 2

aint that pin/pout=efficiency?

Answer 3

*correction. Not nu = 1, but eta = 1, \( \eta = 1 \)

For the record, if it is absolutely energy inefficient, then \( \eta = 0 \).

Answer 4

my oh my means i screwed up!!

Answer 5

yeah but i am having a problem of figuring out the problem

Answer 6

i mean the answer is fine but can you explain it so that i can figure it out my self next time

Answer 7

If a process, is perfectly efficient, then
Energy out = Energy in.
P_out = P_in

Therefore
\[ \eta = \frac{P_{out}}{P_{in{\}} = 1 \]

Answer 8

\[ \eta = \frac{P_{out}}{P_{in}} = 1 \]

Answer 9

oh ok

Answer 10

If it absolutely inefficient, then P_out = 0 and
\[ \eta = \frac{P_{out}}{P_{in}} = 0 \]

If half the energy in comes out, then \[ P_{out} = \frac{1}{2} P_{in} \] and therefore
\[ \eta = \frac{P_{out}}{P_{in}} = \frac{1}{2} \]

So you can see, this is very natural definition of efficiency. The quantity \[ \eta \] is the fraction of the input that is converted into output.

Answer 11

im confused what is the answer?