Communication with submerged submarines via radio waves is difficult because seawater is conductive and absorbselectromagnetic waves. penetration into the ocean is greater at longer wavelengths, so the united states has radioinstallations that transmit at 76 hz for submarine communications. what is the approximate wavelength of those extremelylow-frequency waves? a. 500 kmb. 1000 kmc. 2000 kmd. 4000 km

Ablock of mass m slides on a horizontal frictionless table with an initial speed v0 . it then compresses a spring of force constant k and is brought to rest. the acceleration of gravity is 9.8 m/s2. how much is the spring compressed x from its natural length? 1) x = v0*sqrt(k/(mg)) 2) x=v0*sqrt(m/k) 3) x=v0*((mk)/g) 4) x=v0*sqrt(k/m) 5) x=v0*(m/kg) 6) x=v0*sqrt((mg)/k) 7) x=(v0)^2/(2g) 8) x=v0*(k/(mg)) 9) x=(v0)^2/(2m) 10) x=v0*((mg)/k)