Car Velocity Question

[bns1201]

Homework Statement

Part 1 Consider a car which is traveling along a straight road with constant acceleration a. There are two checkpoints, A and B , which are a distance 81.4 m apart. The time it takes for the car to travel from A to B is 5.89 s.

Part 2 Find the velocity VB for the case where the acceleration is 7.45 m/s^2.

The Attempt at a Solution

acceleration multiplied by the final time does not give me the answer

 

[danago]

What is VB? Is that supposed to be the velocity once it reaches checkpoint B?

 

[bns1201]

yea my browser won't load the functions so it should read V(sub)B which is the velocity once it reaches checkpoint B.

 

[danago]

Perhaps start by finding what the velocity at checkpoint A is.

 

[bns1201]

how would you go by doing that?

 

[bns1201]

anyone? I have no clue how to find the velocity at either checkpoints with the given data

 

[Delphi51]

Take A to be the initial point, time = 0.
Then for the trip to B you know d, t, and a. Don't know Vi.
You could make progress with d = Vi*t + 0.5a*t^2 which has only one unknown.
There is another formula like that with a Vf instead of a Vi which would get you to the answer in one step.