In order to find the acceleration of the object, use the following expression:
[tex]a=\frac{v_2-v_1}{t_2-t_1}[/tex]
where v1 is the speed of the object at time t1 and v2 the speed at time t2.
In this case, based ont the given graph, you have:
t1 = 10.0s
t2 = 30.0s
v1 = 1m/s
v2 = 0m/s
replace the previous values into the formula for a and simplify:
[tex]a=\frac{0\frac{m}{s}-1\frac{m}{s}}{30.0s-10.0s}=0.05\frac{m}{s^2}[/tex]
Hence, the acceleration between the given time interval is 0.05m/s^2
