Answer:
<em>The average speed of the train is 45 km/h</em>
Explanation:
<u>Speed</u>
It's defined as the distance (d) per unit of time (t) traveled by an object. The formula is:

Let's call x the total distance covered by the train. It covered d1=1/3x with a speed of v1=25 km/h. The time taken is calculated solving for t:



Now the rest of the distance:
d2 = x - 1/3x = 2/3x
Was covered at v2=75 km/h. Thus the time taken is:



The total time is:



Simplifying:

The average speed is the total distance divided by the total time:

Simplifying:

The average speed of the train is 45 km/h
<span>The correct answer is C) a motor.
In particular, we are talking about an AC motor, which produces an alternating current. In an AC motor, a coil is immersed in a rotating magnetic field. Due to the motion of the magnetic field,the angle between the direction of the field and the surface enclosed by the coil changes. As a result, the magnetic flux through the coil changes over time (the magnetic flux is given by:
</span>

<span>
where B is the intensity of the magnetic field, A is the area enclosed by the coil and </span>

<span> is the angle between the direction of B and the perpendicular to the plane of the coil). For Faraday-Newmann-Lenz law, this change in flux induces an electromotive force (emf) into the coil, according to:
</span>

<span>
where the numerator is the variation of magnetic flux and dt is the time interval. This emf in the coil produced an electrical current in the circuit.</span>
Answer:
what are u asking there isnt a question
Answer:
1.70 J
Explanation:
The heat dissipated is the difference in the kinetic energies.
This is given by

and
are the initial and final velocities.
With <em>m</em> = 0.175 kg,

The negative sign appears because energy is lost.