Yup the correct answer is A jus finished the quiz :)
hope i helped^_^
Two small spheres spaced 20.0 cm apart have equal charge.
How many excess electrons must be present on each sphere if the magnitude of the force of repulsion between them is 4.57 x 10-21 N?
Number of Electrons = ?
Answer:
C. 2.0 cm
Explanation:
The magnetic field around the wire at point M is given by Biot-Savart Law:

where,
B = Magnetic field = 50 μT = 5 x 10⁻⁵ T
I = current = 5 A
μ₀ = permeability of free space = 4π x 10⁻⁷ N/A²
R = distance of point M from wire = ?
Therefore,

R = 0.02 m = 2 cm
Hence, the correct option is:
<u>C. 2.0 cm</u>
<h2>
Average speed of transit train is 60 mph</h2>
Explanation:
Average speed of passenger train = 45 mph
Time taken from station A to station B for passenger train = 10:00 - 6:00 = 4 hours
Distance between station A to station B = 45 x 4 = 180 miles.
Time taken from station A to station B for transit train = 4 - 1 = 3 hours
Distance between station A to station B = Average speed of transit train x Time taken from station A to station B for transit train
180 = Average speed of transit train x 3
Average speed of transit train = 60 mph
Average speed of transit train is 60 mph
We ran out of fuel would be the correct answer - gas is too <span>ambiguous and could be understood and gasoline.</span>