Respostas

2013-08-12T16:55:22-03:00
V = 20                            V = s/t
S = 100               
T = ?


20  =  100
        ---------
           t

20t = 100
t = 100
    --------
       20

t = 5


V = V(inicial) + a * t
20 = 0 + a * 5
20 = 5a
a = 20/ 5
a = 4
2013-08-12T17:08:47-03:00
Utilizando a Equação de Torricelli, temos:

V^2=V_0^2+2a\Delta S\\\\
0^2=20^2+2a\cdot100\\\\
0=400+200a\\\\
200a=-400\\\\
a=\dfrac{-400}{200}\\\\
a=-2\;m/s^2