Answer:
3 m/s
Explanation:
Kinetic energy of a body is given by the formula 
. Let's replace everything we have and solve for what's left.
or 
The correct answer is A. Electromagnetic waves can transfer energy without a medium. Heat can be transferred through a vacuum only via radiation. Infrared waves are electromagnetic waves that does not require a medium to travel. Heat is transferred in a vacuum in the form of infrared waves.
We don't see any circuit diagrams.
This worries us for a few seconds, until we realize that we don't know anything about the experiment described in the problem either, so we don't have to worry about it at all.
In order to know how long it has been falling for you take the final velocity "49m/s" and divide it by the acceleration "9.8m/s" and get 5, since you have been using seconds in the calculations the answer is 5 seconds. (Fun fact, it is actually 9.82m/s per second since it accelerates and they rounded it down.)
The color green is the the color of light in the visible spectrum which appears the brightest, but with proper illumination, the color green-yellow appears to be the brightest, with the human eye having the maximum sensitivity of 555nn
