a. 
The equivalent resistance of a series combination of two resistors is equal to the sum of the individual resistances:

In this circuit, we have

Therefore, the equivalent resistance is

b. 5.8 V, 3.2 V
First of all, we need to determine the current flowing through each resistor, which is given by Ohm's law:

where V = 9.00 V and
. Substituting,

Now we can calculate the potential difference across each resistor by using Ohm's law again:


Answer:
42.11 years old
Explanation:
Given that:
In 2000, a 20-year-old astronaut left Earth to explore the galaxy; her spaceship travels at 2.5 x 10^8 m/s. She returns in 2040
To find her age we use:

Δtm is time interval for the observer stationary relative to the sequence of
events = 2040 - 2000 = 40 years
Δts is is the time interval for an observer moving with a speed v relative to the sequence of event
v = velocity = 2.5 x 10^8 m/s
c = speed of light = 3 x 10^8 m/s

Here age in 2000 is 20 year, therefore when she appear she would be 20 year + 22.11 year = 42.11 years old
Friction is the opposition offered to the movement of a surface on another and depends on the nature of the surfaces in contact.
<h3>What is friction?</h3>
The term friction refers to the opposition that is offered by surfaces in contact when they move over each other. The question is incomplete but I will try to help you the much I can.
Now recall that fricton only depends on the nature of the surfaces in contact. The friction is te reason when heat is provides in the moving parts of machines.
Learn more about friction: brainly.com/question/15117038
For this, we need the formula:
V = k q / r
where k is the Coulombs law constant = 9 x 10^9 N
q is the charge of the hydrogen nucleus (proton) = <span>1.6 x 10^-19 C</span>
r is the distance
Simply plug in the values and solve for V
Weeds are very important agronomically because they reduce the yield of crops in three ways: by competing with the crop for water, light and nutrients, by interfering with crop harvest, and by contaminating harvested products with weed seeds and toxins. Weeds can reduce yield up to 50% and are responsible for millions of dollars in crop losses each year.
It’s biotic factor would be competition as Competition can be defined as an interaction between organisms or species, in which the fitness of one is lowered by the presence of another.