physics
posted by abbie .
A car is traveling at a constant speed of 27.1 m/s on a highway. At the instant this car passes an entrance ramp, a second car enters the highway from the ramp. The second car starts from rest and has a constant acceleration. What acceleration must it maintain, so that the two cars meet for the first time at the next exit, which is 2.81 km away?

To travel 2.81 km, and reach the next exit at the same time, the time spent getting there must be
t = 2810/27.1 = 103.7 s.
Require that
(1/2) a t^2 = 27.1 t, and
solve for a, using the t from above.
a = 54.2/t = 0.523 m/s^2