After starting the race from rest, sprinter Usain Bolt reached a maximum speed of 12.0 m/s in 2.0 s while running the 100-m dash. What was his acceleration over the first 2.0 s? please help me

The electric field between square plates of a parallel-plate capacitor has magnitude e. the potential across the plates is maintained with constant voltage by a battery as they are pulled apart to twice their original separation, which is small compared to the dimensions of the plates. the magnitude of the electric field between the plates is now equal to a)e b)e/4 c)e/2 d)4e e)2e