The volume of the cube is (2cm x 2cm x 2cm) = 8 cm³ .
The density of the cube is
(the mass of the cube, in grams) / (8 cm³) grams per cm³ .
That's the best I can do, because you haven't told us the cube's mass.
<u>Answer:</u>
The force on the 2.00-uC charge is 
<u>Explanation:</u>
We know that force between two charges is given by Coulomb’s law,
Where k = Coulomb’s constant =
And q1 and q2 are the charges given to be = -4.00-uC and 2.00-uC charges
And r = distance between the charges = 20 cm = 0.2 m
Substituting the given values in the formula we get force applied on 
charge,
F = attractive force which is the required answer.
They have a diagonal relationship
I think it’s A. Mining and logging are huge factors
v = speed of the source of sound or the train towards the listener or switchman = 40 m/s
V = actual speed of sound = 340 m/s
f = actual frequency of sound as emitted from source or the train = 1000 Hz
f' = frequency as observed by the listener or by switchman = ?
Using Doppler's law , frequency observed by a listener from a source moving towards it is given as
f' = V f /(V - v)
inserting the values
f' = 340 x 1000 /(340 - 40)
f' = 340 x 1000/300
