Which type of wave does not require a medium to travel through? a. rope wave b. radio wave c. slinky wave d. tuning fork wave

The answer is radio wave, waves on the electromagnetic spectrum don't need a medium

The answer is 4f======since electrostatic force is given by    we let f be the electrostatic force when  r = 1 m    if we let  denote the electrostatic force when the distance is decreased so that r = 0.5m, then    we established earlier that f = kq₁q₂. therefore    the force will now be 4f.