Posted by **a** on Tuesday, September 13, 2011 at 12:16am.

Two cars start from rest at a red stop light. When the light turns green, both cars accelerate forward. The blue car accelerates uniformly at a rate of 4.6 m/s2 for 4.4 seconds. It then continues at a constant speed for 8.5 seconds, before applying the brakes such that the car’s speed decreases uniformly coming to rest 247 meters from where it started. The yellow car accelerates uniformly for the entire distance, finally catching the blue car just as the blue car comes to a stop.

2)How fast is the blue car going 10.4 seconds after it starts?

3)How far does the blue car travel before its brakes are applied to slow down?

4)What is the acceleration of the blue car once the brakes are applied?

- physics -
**Henry**, Wednesday, September 14, 2011 at 5:40pm
1. V1 = Vo + at,

V1 = 0 + 4.6*4.4 = 20.24m/s.

2. V2 = V1 = 20.24m/s after 10.4s.

3. D = di + d2,

d1 = Vo*t + 0.5at^2,

d1 = 0 + 0.5*4.6*(4.4)^2 = 44.53m.

d2 = Vt = 20.24 * 8.5 = 172m.

D = 44.53 + 172 = 217m.

4. Ds = 247 - 217 = 30m = Stopping

distance.

a = (Vf^2 - Vo^2) / 2d,

a = (0 -(20.24)^2 / 60 = -6.83m/s^2.

## Answer this Question

## Related Questions

- Physics - Two cars start from rest at a red stop light. When the light turns ...
- Physics - Two cars start from rest at a red stop light. When the light turns ...
- Physics - Two cars start from rest at a red stop light. When the light turns ...
- physics - please somebdy help me solveing this. Two cars start from rest at a ...
- physics - Two cars start from rest at a red stop light. When the light turns ...
- physics with 6 questions - Two cars start from rest at a red stop light. When ...
- Physics - Two cars start from rest at a red stop light. When the light turns ...
- physics - Two cars adjacent to each other on a highway. The first car ...
- physics - Consider a horizontal road with such a set of traffic lights, each ...
- physic - a car sits still at a red light. once the light turns green, the driver...