Answer:
The technique in which people use machines to learn how to control their bodies is known as D, Biofeedback.
Explanation:
Biofeedback is a variety of different machines that help people learn how to control their bodies depending on their specific needs, varying from things like scalp sensors, electrocardiographs, electromyographs and more.
Answer:
Explanation:
Reddening of sun's rays at sunset and sunrise is due to scattering of light . The white light consisting of seven colours coming from the sun are scattered in different directions when they fall on the air particles present in atmosphere . Red coloured light scatters least and it travels straight forward to the viewer on the earth . On the other hand other colours scatter most and therefore they go out of area of vision for the viewer on the earth . Since only red colour reaches the eye of the viewer , sun's ray appear red . This happens during sunrise and sunset . It is so because during this period , sun rays travel far greater distance through atmosphere , so scattering is most pronounced .
Answer:
Therefore,
The frequency heard by the engineer on train 1
Explanation:
Given:
Two trains on separate tracks move toward each other
For Train 1 Velocity of the observer,
For Train 2 Velocity of the Source,
Frequency of Source,
To Find:
Frequency of Observer,
(frequency heard by the engineer on train 1)
Solution:
Here we can use the Doppler effect equation to calculate both the velocity of the source 
and observer 
, the original frequency of the sound waves 
and the observed frequency of the sound waves 
,
The Equation is
Where,
v = velocity of sound in air = 343 m/s
Substituting the values we get
Therefore,
The frequency heard by the engineer on train 1
