PLZ HELP
A wave has a wavelength of 4.9 m and a velocity of 9.8 m/s. The medium through which this wave is traveling is then heated so that the velocity is doubled.

If the frequency remains constant, what is the wavelength of the heated wave?

2.5 m
9.8 m
14.7 m
19.6 m

the wavelenght is 9.8 meters

Explanation:

We can use the relationship:

Velocity = wavelenght*frequency.

Initially we have:

wavelenght = 4.9m

velocity = 9.8m/s

then:

9.8m/s =  4.9m*f

f = 9.8m/s/4.9m =  2*1/s

now, if the velocity is doubled and the frequency remains the same, we have:

2*9.8m/s = wavelenght*2*1/s

wavelenght = (2*9.8m/s)*(1/2)s = 9.8 m

less than one you can't create energy