3.Referring to the displacement vs time graph here given, the velocity of the mobile is zero:

a)between the bottom of 10 s and the top of 10 s
b)between the bottom of 15 s and the top of 15 s
c)from 5 s to the top of 15 s
d)between 5 s and 10 s and between 10s and 15 s
e)none of a), b), c) and d)

10 Time (s) 15 20 Postion ( m)