Answer:
the answer is a)5.82s
Explanation:
Hello!
The first thing we must understand to solve this exercise is that a capacitor has the following characteristic function

where
Vo=initial voltage
V=voltage in an instant of time
t=time
R=resistance=4000Ω
C=capacitance=2.1-mF=0.0021F
we must consider that the final voltage is half of the initial voltage so we deduce the following equation
V=Vo/2
Now we replace in the initial equation, and start an algebraic process to find t

finally with the equation ready, we use the resistance and capacitance values to find the time value

the answer is a)5.82s
Heat will flow from the water into the air by convection .
<h2>
Answer:</h2>
<em><u>Running water on the Surface of Earth.</u></em>
<h2>
Explanation:</h2>
Weathering can be defined as the phenomenon of breaking or disintegration of the rocks, minerals, soil etc. due to coming in contact with the Earth's atmosphere such as the Water, Wind, Organisms etc.
In this process the rocks, minerals disintegrate into lot of small particles.
But the rate of weathering on Earth is at a very unusual or unique rate because Earth's surface has the presence of the running water that leads to the high rate of surface weathering.
<em><u>Therefore, the reason of Earth's rapid weathering rates is Running water on the Surface of Earth.</u></em>
<em><u></u></em>
The magnetic force experienced by the proton is given by

where q is the proton charge, v its velocity, B the magnitude of the magnetic field and

the angle between the direction of v and B. Since the proton moves perpendicularly to the magnetic field, this angle is 90 degrees, so

and we can ignore it in the formula.
For Netwon's second law, the force is also equal to the proton mass times its acceleration:

So we have

from which we can find the magnitude of the field:
(a) Differentiate the position vector to get the velocity vector:
<em>r</em><em>(t)</em> = (3.00 m/s) <em>t</em> <em>i</em> - (4.00 m/s²) <em>t</em>² <em>j</em> + (2.00 m) <em>k</em>
<em>v</em><em>(t)</em> = d<em>r</em>/d<em>t</em> = (3.00 m/s) <em>i</em> - (8.00 m/s²) <em>t</em> <em>j</em>
<em></em>
(b) The velocity at <em>t</em> = 2.00 s is
<em>v</em> (2.00 s) = (3.00 m/s) <em>i</em> - (16.0 m/s) <em>j</em>
<em></em>
(c) Compute the electron's position at <em>t</em> = 2.00 s:
<em>r</em> (2.00 s) = (6.00 m) <em>i</em> - (16.0 m) <em>j</em> + (2.00 m) <em>k</em>
The electron's distance from the origin at <em>t</em> = 2.00 is the magnitude of this vector:
||<em>r</em> (2.00 s)|| = √((6.00 m)² + (-16.0 m)² + (2.00 m)²) = 2 √74 m ≈ 17.2 m
(d) In the <em>x</em>-<em>y</em> plane, the velocity vector at <em>t</em> = 2.00 s makes an angle <em>θ</em> with the positive <em>x</em>-axis such that
tan(<em>θ</em>) = (-16.0 m/s) / (3.00 m/s) ==> <em>θ</em> ≈ -79.4º
or an angle of about 360º + <em>θ</em> ≈ 281º in the counter-clockwise direction.