Answer :
b) 4m/s/s
This is because you divide the speed you reach, by the time it takes to get to that speed:
12m/s ÷ 3s = 4m/s/s
The units come from what you divide, meters per second ÷ seconds this can be written as m/s/s or ms-²
The answer id 4 m/s/s this is because 12/3 = 4 and an easy way to get the units is put the two together
Acceleration = m/s (Meters per second)
Time = s (Seconds)
m/s/s = Meters per second/ Per second
Acceleration = m/s (Meters per second)
Time = s (Seconds)
m/s/s = Meters per second/ Per second