Work = force x distance.
force = mass x acceleration
work = mass x acceleration x diastance
use acceleration of gravity in this problem
W (J) = m (kg) x a (m/s/s) x d (m)
W = 78 x 9.8 x 6
W = 4586.4
Answer:

Explanation:
q = Charge in the potassium ion = 
e = Charge of electron = 
= Change in potential = 
Change in electric potential is given by

The energy is 
When it comes to wave behavior, there are parameters called wavelength and frequency. These two are related by speed of the radiowave. Radiowaves are electromagnetic waves which travels as fast as light. The wavelength is the distance while frequency is the reciprocal of time. When you multiply them both, you get the electromagnetic wave's speed. The equation is c = wavelength*frequency, where c is the speed of light equal to 3 x 10^8 m/s.
3 x10^8 m/s = wavelength/104.9 x 10^6 Hz (Hertz is 1/s)
wavelength = 2.86 meters