I would say d because the student isn’t moving, the Ferris wheel is.
There are three factors:
The charge of the two objects. The electric force is proporcional to the product of the charges of both objects.
The distance that separetes them. The electric force is proportional to the inverse of the squared distance that separates the objects.
The media. The electric force constant of proportionality depends on the media: air, water, oil, glass.
Answer:
The distance between the charges is 9.5 cm
(c) is correct option
Explanation:
Given that,
Charge 
Force F = 1 N
We need to calculate the distance between the charges
Using Coulomb's formula

Where, q = charge
r = distance
F = force
Put the value into the formula




Hence, The distance between the charges is 9.5 cm
Answer:
A) 2.89 × 105 N/C, radially inward
Explanation:
The magnitude of the electric field generated by a charged sphere is given by the following formula:
( 1 )
k: Coulomb's constant = 8.98*10^9 Nm^2/C^2
Q: charge of the sphere = -6.50*10^-6 C
r: distance from the center of the sphere to the point in which E is calculated
r = 0.150m + 0.300m = 0.450 m
You replace the values of Q and r in the equation (1):

The electric field points radially inward because the charge is negative.
hence, the answer is:
A) 2.89 × 105 N/C, radially inward
Mu = 8.66 × 10^25 kg
Explanation:
centripetal force = gravitational force

where
m = mass of moon Ariel
mu = mass of Uranus
r = radius of Ariel's orbit
v = Ariel's velocity around Uranus
To find the velocity, we need to find the circumference of the no orbit and then divide it by the period (2.52 days):
circumference = 2πr = 2π×(1.91 × 10^8 m)
= 1.2 × 10^9 m
period = 2.52 days × (24 h/1 day)×(3600 s/1 hr)
= 2.18 × 10^5 s
v = (1.2 × 10^9 m)/(2.18 × 10^5 s)
= 5.5 × 10^3 m/s
(5.5 × 10^3 m/s)^2/(1.91 × 10^8 m) = (6.67 × 10^-11 m^3/kg-s^2)Mu/(1.91 × 10^8 m)^2
Solving Mu,
Mu = 8.66 × 10^25 kg