The book that weighs less
vector b is the answer...............
Explanation:
Position-time graphs measure/express the position of a skater over time relative to the start or finish of the race (depends on how it is used). Note: are the skaters in line vertically or horizontally? Like is one directly behind the other or are they next to each other?
If the two skaters are in line horizontally with each other, then their position will be the same relative to the start or finish of the race. This means if one passes the other one, the position would be different for all times after they pass. On the graph, it would look like one single line at the start (as position is same) which splits into 2 (representing the new difference in position due to 1 passing the other.
If the two skaters are in line vertically, their lines on the graph will appear parallel to each other (assuming they are going same speed) because the position is changing at the same rate, one is just reaching the same point after the other. If the skater behind overtakes the one in front. The lines on the graph will cross and continue either in parallel but with the other line on top to represent the moment where their position is the same right before they pass and after, where the second skater is now in front.
Hope this helped!
Answer:

Explanation:
The volume charge density is defined by ρ =
(Equation A), where Q is the charge and V, the volume.
The units in the S.I. are
, so we have to express the radius in meters:
inner radius = 
outer radius = 
Now, we know that the volume of the sphere is calculated by the formula:
, and as we have an spherical shell, the volume is calculated by the difference between the outher and inner spheres:
V =
, where
is the outer radius and
is the inner radius.
Replacing the volume formula in the Equation A:
ρ = 
ρ = 
Replacing the values of the outer and inner radius whe have:
ρ = 
ρ = 