A drag racer, starting from rest, speeds up for 393 m with an acceleration of +16.3 m/s2. A parachute then opens, slowing the car down with an acceleration of -5.51 m/s2. How fast is the racer moving 3.31E+2 m after the parachute opens?

To find the final velocity of the racer, we can break down the problem into two parts: the acceleration phase and the deceleration phase.

1. Acceleration phase:
Using the equation for constant acceleration, we can find the velocity during the acceleration phase:
a = acceleration
d = distance
vi = initial velocity
vf = final velocity

vf^2 = vi^2 + 2ad

Given:
a = +16.3 m/s^2
d = 393 m
vi = 0 (starting from rest)

Substituting the values into the equation:
vf^2 = 0^2 + 2 * 16.3 * 393

Simplifying:
vf^2 = 12798.6

Taking the square root of both sides:
vf ≈ 113.28 m/s

2. Deceleration phase:
Using the same equation, we can find the velocity during the deceleration phase:
Given:
a = -5.51 m/s^2
d = 3.31E+2 m (331 m)

vf^2 = vi^2 + 2ad

Substituting the values into the equation:
vf^2 = (113.28)^2 + 2 * (-5.51) * 331

Simplifying:
vf^2 = 12798.6 - 3639.22

vf^2 ≈ 9168.38

Taking the square root of both sides:
vf ≈ 95.80 m/s

Therefore, the racer is moving approximately 95.80 m/s 3.31E+2 m after the parachute opens.