Answer:
Because always when we do an experiment, we need something to compare.
For example, if we want to see how much change a given color paint when we add different amounts of white paint to it, we need to have at least one sample of pure color paint, so we can compare it whit the ones with mixed paints.
Well, the case of the polygraph is exactly the same, we need to have a baseline, so we the interviewer can see if for some questions there is a change in the line compared with the baseline.
The answer is if matter is created or destroyed :) Hope this helped you out at least some
The best answer is B. If you curve them away, they have a less tendency to be attracted to the pair of charges and would stay around the pair instead of interacting with them.
Answer: The answer: The car is moving away from you.
Both A and C are true as Car can be moving in line away from you or has component of velocity in opposite direction.
Explanation:The decrease in the frequency of the sound is the result of Doppler's effect. A/c to Doppler's effect the frequency of received sound of source is changed if it is moving relative to the receiver, i.e. the distance between them is changing due to motion.
The general formula of Doppler's Effect is attached as the picture.
In this formula v_D is the velocity of Detector i.e the receiver relative to wind. While v_s is the velocity of source relative to wind and v is the velocity of sound.
The Doppler's effect is not effected by the velocity of wind as the wind itself could not change the distance between the two objects i.e. you and the car. Wind velocity can change the speed of sound and its wavelength but the change does not effect the frequency.
Hence if we assume the car to be moving with velocity v_c and you are stationary
hence the frequency is reduced.