<span> the </span>electric field<span> direction about a </span>positive<span> source </span>charge<span> is always directed away from the </span>positive<span> source. And the </span>electric field <span>direction about a negative source </span>charge<span> is always directed toward the negative source.</span>
It's called the periodic table because it arranges the elements the into repeating sets known as periods. this is defined by the <span>covalence of an element and the number of electrons i has in its outermost shell. I feel the the Best answer would be B. sorry if im wrong but i hope i helped :)</span>
Answer:

Explanation:
Given that,
Initial velocity, u = -5 m/s
Final velocity, v = -22 m/s
Time, t = 3s
We need to find the acceleration of the car. The formula of it is given by :
Acceleration,

So, the acceleration of the car is
.
Answer:
The first harmonic is: 250Hz, second harmonic 500Hz, third harmonic 750Hz.
Explanation:
Use the frequency f, speed v, and wavelentgh L relationship:

We are given the speed v=400 m/s. The base wavelength on a string of length 80cm is twice the length of the string (a "half wave" along the full length of the string), so:

The fundamental frequency (first harmonic) is 250 Hz
The second harmonic is produced by one full wave across the string (adding one node in the middle), so L=80cm in this case, therefore the second harmonic frequency is: f2 = 2*250=500Hz
the third harmonic add another node (and a half wave) to the pattern and the wavelength will be 2/3 of 80cm, so f3=3*250Hz = 750Hz