The answer to your question is b
In an experiment if doubling the manipulated variable results in doubling of the responding variable the relationship between the variable is a direct. Having a direct relationship means that the<span> relationship between two numbers or other variables where an increase or decrease in one variable causes the same change to the other variable.</span>
I'm not sure about the magnitude, but the direction of the normal force is upward.
Answer:
Naturally occurring radio waves are made by lightning or by astronomical objects. Artificially generated radio waves are used for fixed and mobile radio communication, broadcasting, radar and other navigation systems, communications satellites, computer networks and innumerable other applications.
Explanation: