fisica1-youn-e-freedman-exercicios-resolvidos

2.70: The position of the cars as functions of time (taking x 1 = 0 at t = 0) are
1 2
x1 = at , x2
= D − v0t.
2
The cars collide when x 1 = x 2 ; setting the expressions equal yields a quadratic in t,
1
2
at
2
+ v t − D
0
= 0,
the solutions to which are
t =
1
a
2
1 2
( v0 + 2aD
− v0
) , t = ( − v0
+ 2aD
− v0
).
a
The second of these times is negative and does not represent the physical situation.
2
b) v1 = at = ( v0
+ 2aD
− v0
)
c)