Respuesta :

Aceleration = change in speed / time for the change

Change in speed = (later speed) minus (earlier speed)                                

Change in speed = (1 m/s) - (3 m/s)  =  -2 m/s

Time for the change = 2 seconds

Acceleration = (-2 m/s) / (2 seconds)

Acceleration = -1 m/s²