Answer:
Distance between the charges, r = 0.8 meters
Explanation:
Given that,
Charge 1, 
Charge 2, 
Repulsive force between charges, F = 0.66 N
Let r is the distance between charges. The formula for the electrostatic force is given by :


r = 0.8009 meters
or
r = 0.8 meters
So, the distance between the charges i 0.8 meters. Hence, this is the required solution.
Answer:
1.06 secs
Explanation:
Initial speed of sled, u = 8.4 m/s
Final speed of sled, v = 5.8 m/s
Coefficient of kinetic friction, μ = 0.25
Using the impulse momentum theory, we know that the impulse applied to the sled is equal to change in momentum of the sled:
FΔt = mv - mu
where m = mass of the object
Δt = time interval
F = force applied
The force applied on the sled is the frictional force, which is given as:
F = -μmg
where g = acceleration due to gravity
Therefore:
-μmgΔt = mv - mu
-μmgΔt = m(v - u)
-μgΔt = v - u
Making Δt subject of formula:
Δt = (v - u) / -μg
Δt = (5.8 - 8.4) / (-0.25 * 9.8)
Δt = -2.6/ -2.45
Δt = 1.06 secs
It took the sled 1.06 secs to travel from A to B.
Answer:
Average speed, v = 11.37 m/s
Explanation:
Given that,
The distance covered by the traveler, d = 217 miles = 349228 meters
Time taken, 
or t = 30708 s
We need to find the average speed for this trip. The average speed is given by :

v = 11.37 m/s
So, the average speed for this trip is 11.37 m/s. Hence, this is the required solution.