Constant Acceleration

Question

A car moves with a constant acceleration of 12.0m/s² in the positive x-direction. After moving 355m, its speed is now 175.0 m/s. What was the initial speed of the car? How long did it take the car to move to 455m?

Answer 1

a = 12

d= at^2/2 +vot where vo = initial velocity

355 = 6t^2 + 175, vot=175

6t^2 =180

t^2 = 30

t =sqr30 = about 5.48 seconds

vo(sqr130) = 175

vo = 175/sqr30 = about 32 m/sec = initial speed of the car

455 = 6t^2 +32t

6t^2 + 32t -455

use the quadratric formula

t = about 6.44 seconds to reach 455 m