Can someone explain 3 i don't understand

Alightning strike consists of charge moving from a cloud to the ground . in one particular case, the electrons in a lightning strike are confined to travel within a radius of 1.5 m and to move at a speed of 5.0 x 10 m/s. if the density of electrons in the strike is 10'15 electrons/m what current is carried by the lightning ?

Which sound characteristic is not affected by the relative motion of an object

Avehicle accelerates from 0 to 30 m/s in 10 seconds on a straight road