Answer:
100 ly are 
Explanation:
The speed of light is, by definition (we define this and derive a definition of distance from there nowadays), c=299792458m/s. We want to know, at this speed, how much distance the radio signals travel in 100 years. Since each year has 365 days (not a leap one though), each day has 24 hours, each hour has 60 minutes and each minute has 60 seconds, the number of seconds in a year will be (365)(24)(60)(60)=31536000, so the distance traveled by the waves in 100 years will be:
, which, of course, are 100 light years.
Answer:
f = pl / (l + p)
Explanation:
1/f = 1/p + 1/l
Find the common denominator of the right hand side.
1/f = l/(pl) + p/(pl)
Add:
1/f = (l + p) / (pl)
Take the inverse of both sides:
f = pl / (l + p)
A) initial volume
We can calculate the initial volume of the gas by using the ideal gas law:

where

is the initial pressure of the gas

is the initial volume of the gas

is the number of moles

is the gas constant

is the initial temperature of the gas
By re-arranging this equation, we can find

:

2) Now the gas cools down to a temperature of

while the pressure is kept constant:

, so we can use again the ideal gas law to find the new volume of the gas

3) In a process at constant pressure, the work done by the gas is equal to the product between the pressure and the difference of volume:

by using the data we found at point 1) and 2), we find

where the negative sign means the work is done by the surrounding on the gas.