It would be 12hz because it
Potential energy = mass x gravity x height
P.E = 4 x 9.8 x 3
P.E = 117.6 J
Answer:Magnetic fields are invisible, at least usually. But scientists from NASA's Space Sciences Laboratory have made them visible as "animated photographs," using sound-controlled CGI and 3D compositing.
Explanation:
Power= energy/time= 360/(2*60)=3 W thats 2nd option
