Power is the rate of doing work or using energy.
The unit of power is the watt.
1 watt = 1 joule per second
<span>Commutator
is the moving part of the electric motor and periodically reverses the current
direction between the rotor and the external circuit.One end of the coil is
attached to each half of the commutator.
Commutator are used so when electricity flows through the circuit, the
coil will rotate continually in the same direction.</span>
The car travels at a speed of 25m/s.
<u>Explanation:</u>
Given-
Mass, m = 1500kg
Coefficient of friction, μk = 0.47
Distance, x = 68m
Speed, s = ?
We know,

and
F = μ X m X g
Therefore,
μ * m * g = m * a
μ * g = a
Let, g = 9.8m/s²
So,


We know,

where, v is the final velocity
u is the initial velocity
a is the acceleration
s is the distance
If the car comes to rest, the final velocity, v becomes 0.
So,

The car travels at a speed of 25m/s.
The answer is Carbonic acid