Answer:
C. X: Allows current to flow into the commutator
Y: Conducts current to the armature and reverses direction of current
Explanation:
Carbon brush is a motor brush that acts as the conducting block for current between the stator and the rotor of a motor.It is made of carbon blocks.The brush is held in place using a spring that ensures its contact position with the commutator.The commutator prevents the torque on the motor from reversing whenever the coil is rotating in the magnetic field.
Answer:

Explanation:
As we know by energy conservation
All its kinetic energy will convert into thermal energy to raise its temperature

now divide both sides by mass of the object

so change in temperature is given as



Answer:
12.974 m/s
Explanation:
t = Time taken
u = Initial velocity
v = Final velocity
s = Displacement
g = Acceleration due to gravity = 9.81 m/s²
= Coefficient of friction =0.66
a = Acceleration = 

Car's original speed before braking was 12.974 m/s
Radio waves have the longest wavelength
Answer:
Ethnomethodology theory
Explanation:
Take note of the fact that we are told Kevin worries that the police will stop and question him even though he has not done anything wrong.
This statement shows us that Kevin already understood his society from past experiences, and thus he tries to avoid social interactions with particular member of his society (the police) who may be show discrimination towards him.