Answer:

Explanation:
We know that for a capacitor
, where <em>Q </em>is the charge of one plate, <em>C</em> the capacitance and <em>V</em> the potential between the plates.
We also know that
, since
is the surface charge density and <em>A</em> the area of the plate (both equal in our case).
Putting all together:

Which for our values is:

Where we notice that the S.I. units combination FV/C must not have units (we can verify it directly from their definitions or we notice that
is enough to describe an area).
Answer:
net force= 2000-1000=1000
a=v-u/t=5/20=1/4
m=?
m=f/a
=1000÷1/4=4000kg
Answer: The soil will be
warmer than the water.
Explanation:
The heat (thermal energy) absorbed can be found using the following equation:
Where:
is the heat
is the mass of the element
is the specific heat capacity of the material.
is the variation in temperature
<u>In the case of soil we have:</u>
(1)
Where:


<u>In the case of water we have:</u>
(2)
Where:


Isolating
from both equations:
(3)
(4)
(5)
(6)
Comparing (4) and (6) we can find the soil will be
warmer than the water.
The speed of sound follows the same rules, just like any other speed, if the acceleration is zero.
distance = speed * time
distance = 2m
speed = 333m/s
Solve for time t.