Resposta :
[tex]\boxed{s=s_0+vt}[/tex]
[tex]s=210\ m,\ t=30\ s,\ v=30\ m/s\\\\ 210=s_0+30(30)\ \therefore\ s_0=210-900\ \therefore\\\\ \boxed{s_0=-690\ m}[/tex]
[tex]\boxed{s=s_0+vt}[/tex]
[tex]s=210\ m,\ t=30\ s,\ v=30\ m/s\\\\ 210=s_0+30(30)\ \therefore\ s_0=210-900\ \therefore\\\\ \boxed{s_0=-690\ m}[/tex]