Almost true but not quite.
That would give you the negative of the actual acceleration.
It should be the other way around:
(final v) minus (initial v), then divide by time.
Answer: 1000 Hz · 0,5 m = 500 m/s
Explanation: speed = frequency · wavelength
the more pressure put on the string, the more frequency and higher pitch.
Answer:

Explanation:
From the question we are told that
The electric filed is
Generally according to Gauss law
=> 
Given that the electric field is pointing downward , the equation become

Here
is the excess charge on the surface of the earth
is the surface area of the of the earth which is mathematically represented as

Where r is the radius of the earth which has a value 
substituting values


So

Here
s the permitivity of free space with value

substituting values


A because an earthquake is shaking of tectonic plates