View Full Version : Distance = Rate x Time

rescuepilot16

06-18-2009, 12:01 PM

Simplify:

The Smith Family went on a road trip and on the first day they traveled at a rate of (3x)/y for (y+1)/x hours. How far did they travel?

Wouldn't the equation look something like this: Distance = (3x)/y * (y+1)/x ?

I don't know how to answer this, all help will be greatly appreciated, thanks in advanced!

Loren

06-18-2009, 12:44 PM

Simplify:

The Smith Family went on a road trip and on the first day they traveled at a rate of (3x)/y for (y+1)/x hours. How far did they travel?

Wouldn't the equation look something like this: Distance = (3x)/y * (y+1)/x ?

I don't know how to answer this, all help will be greatly appreciated, thanks in advanced!

Yes. I believe you are correct. However your rate needs to have units assigned to it. In other words, is it miles per hour, km per hour, ft per sec, or what. Your equation is correct assuming the rate is in units per hour, since the time is in hours. Now, you need to simplify your result to make it cleaner. And, until you know what units the rate is in, the distance will have to be expressed as "units". If you know the rate is in km/hr then the distance is so many kms. If the rate is in miles/hr, then the distance is so many miles, etc.

Subhotosh Khan

06-18-2009, 01:08 PM

That is what happens when "non-physics" people set-up psuedo-physics problem - no attention to units or dimension.

I would also liked to have seen "average rate" in there - as opposed to just rate.

rescuepilot16

06-18-2009, 07:23 PM

The problem is 3x/y mph for y+1/x hours, how far did they travel in the one day? I need to simplify it somehow.

Mrspi

06-18-2009, 09:48 PM

The problem is 3x/y mph for y+1/x hours, how far did they travel in the one day? I need to simplify it somehow.

Ok...I believe several folks have reminded you that

distance = rate * time

You are given that the rate is (3x)/y mph

You are given that the time is (y + 1) / x hours

You're looking for the distance. Substitute the known rate and the known time:

distance = rate * time

distance = (3x)/y * (y + 1)/x

distance =[(3x)*(y + 1)] / y*x

Now...simplify the expression on the right side. (Do you see that x is a common factor?)

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