Answer:
Explanation:
According to the free body diagram, in this case, we have:
Recall that the force of friction is given by:
Replacing and solving for the coefficient of kinetic friction:
We have an uniformly accelerated motion. Thus, the acceleration is defined as:
Finally, we calculate :
Answer:
Explanation:
The volume of a sphere is:
V = 4/3 * π * a^3
The volume charge density would then be:
p = Q/V
p = 3*Q/(4 * π * a^3)
If the charge density depends on the radius:
p = f(r) = k * r
I integrate the charge density in spherical coordinates. The charge density integrated in the whole volume is equal to total charge.
Since p = k*r
Q = p*π^2*r^3 / 2
Then:
p(r) = 2*Q / (π^2*r^3)