Complete Question
Suppose a NASCAR race car rounds one end of the Martinsville Speedway. This end of the track is a turn with a radius of approximately 57.0 m . If the track is completely flat and the race car is traveling at a constant 30.5 m/s (about 68 mph ) around the turn.
Required:
a. What is the race car's centripetal (radial) acceleration?
b. What is the force responsible for the centripetal acceleration in this case?
O normal
O gravity
O friction
O weight
Answer:
question a

question b
correct option is option 3
Explanation:
From the question we are told that
The radius is 
The constant speed at which the race car is travelling is 
Generally from the question we are told that the track is completely flat so the only force pulling the car to the middle is the frictional force hence the centripetal force is due to the frictional force
Generally the centripetal acceleration is mathematically represented as

=> 
=> 
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Explanation :
Magnetic field, B = 5.2 T
Electric field, 
The directions of the two fields are perpendicular to each other. Hence the force due to each field will equate each other.
Electrostatic force, F =qE.........(1)
Magnetic force, F = qvB........(2)
From equation (1) and (2)
E = v B




Hence, the correct option is (a).
(2) A permanent magnet always has two poles as the North pole and south pole. The magnetic field lines start from north poles and terminate at the south pole of the magnet.
Hence, the correct option is (C).
Answer: a = 1.32 * 10^18m/s² due north
Explanation: The magnitude of the force required to move the electron is given as
F = ma
The force exerted on the charge by the electric field of intensity (E) is given by
F = Eq
Thus
Eq = ma
a = E * q/ m
Where a = acceleration of charge
E = strength of electric field = 7400N/c
q = magnitude of electronic charge = 1.609 * 10^-6c
m = mass of an electronic charge = 9.109 * 10^-31kg
a = 7400 * 1.609 * 10^-16/ 9.109 * 10^-31
a = 11906.6 * 10^-16 / 9.019 * 10^-31
a = 1.19 * 10^-12 / 9.019 * 10^-31
a = 0.132 * 10^19
a = 1.32 * 10^18m/s²
As stated in the question, the direction of the electric field is due north hence, the direction of it force will also be north thus making the electron experience a force due north ( according to Newton second law of motion)