Answer:
Explanation:
Let the internal resistance be r .
Since in open circuit the volt is 1.55 V , this will be the source voltage .
Source voltage = 1.55
If external resistance be R .
1.55 / (R + r ) = .500
R + r = 3.1 ohm
So sum of internal resistance and external resistance will be 3.1 ohm.
Answer:
A) F=-20.16×10⁹N
B) if the distance doubles, force is 4 times smaller.
Explanation:
q1=-28C
q2=5mC=0.005C
d=25cm=0.25m
Electrostatic force between charges: F=k×q1×q2/d², where k is a coefficient that has the value k=9 × 10⁹ N⋅m²⋅C^(-2) for air.
Thus:
F=9×10⁹×(-28)×0.005/0.25²
F=-20.16×10⁹N
The minus sign indicates attraction.
If distance doubles, d1=2×d, then we have 4d² at the denominator and the force is 4 times smaller.
Answer:
The mass rate of the cooling water required is: 
Explanation:
First, write the energy balance for the condensator: The energy that enters to the equipment is the same that goes out from it; consider that there is no heat transfer to the surroundings and kinetic and potential energy changes are despreciable.

Where w refers to the cooling water and s to the steam flow. Reorganizing,

Write the difference of enthalpy for water as Cp (Tout-Tin):

This equation will let us to calculate the mass rate required. Now, let's get the enthalpy and Cp data. The enthalpies can be read from the steam tables (I attach the tables I used). According to that,
and
can be calculated as:
.
The Cp of water at 25ºC (which is the expected average temperature for water) is: 4.176
. If the average temperature is actually different, it won't mean a considerable mistake. Also we know that
, so let's work with the limit case, which is
to calculate the minimum cooling water mass rate required (A higher one will give a lower temperature difference as a result). Finally, replace data:
