Consider two cars one a chevy, one a Ford. The Chevy is speeding along

1. Sep 13, 2011

tarheels88

Consider two cars one a chevy, one a Ford. The Chevy is speeding along at 50m/s (mph) and the Ford is going half the speed at 30m/s. If the two cars brake to a stop with the same constant acceleration, are either the amount of time required to come to a stop, or the distance traveled prior to stopping influenced by their initial velocity.

I don't really understand the concept of what the question is asking. And no this is not a Homework question.

2. Sep 13, 2011

DaveC426913

Re: Velocity

Is it simply trying to parse the poorly worded paragraph? Here it is broken apart.

Consider two cars one a chevy, one a Ford. The Chevy is speeding along at 50m/s (mph) and the Ford is going half the speed at 30m/s. The two cars brake to a stop with the same constant acceleration.

Is the amount of time required for each vehicle to come to a stop influenced by its initial velocity? Y/N

Prior to each vehicle stopping is the distance it traveled influenced by its initial velocity? Y/N

3. Sep 14, 2011

rcgldr

Re: Velocity

Not that important, but 30 is not half of 50.

4. Sep 14, 2011

Ken G

Re: Velocity

It sounds to me like the question is asking you, what things depend on your speed when you undergo constant deceleration? Constant acceleration allows us to use a collection of well-worn kinematical laws, and here are two:
the change in v2 = 2 a s, where s is the distance traveled.
the change in v = a t, where t is the time.
In both cases, if you are interested in stopping, then v is just the initial velocity, and you get
s = v2/2a
t = v/a
and you clearly see that both the stopping distance, and the stopping time, depend on initial velocity v. You can also see the point commonly stressed in driver's education-- the stopping distance is especially sensitive to initial v, so if you speed, you will have a hard time stopping before you hit an object a fixed distance in front of you.

5. Sep 14, 2011

Lsos

Re: Velocity

Are the stopping distance and/or stopping time affected by a car's initial velocity?

Kind of a long, confusing, mathematically unnecessary and inaccurate way of saying the above.

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook