urgent!A car is travelling at 15 m/s when driver observes that a traffic light 180 m ahead of car turns red.?

Question

. The traffic light is timed for 15 seconds. If the car’s driver wishes to pass the light without stopping just as turns green again, what will be the speed of the car just it passes the light?

Answer 1

Start with the equation

x = 1/2at^2 + v0t + x0 where x =180m, x0 = 0, t = 15 s, and v0 = 15m/s

then you can solve for a.

a =(x -v0t)*2/t^2

a = -0.4 m/s^2 the car slows down.

Now the speed at the light is

v = v0+at = 15 m/s + (-0.4)15 = 9 m/s