1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Help With A Gradient Problem

  1. Oct 14, 2013 #1
    Hi all

    I was hoping someone could help solve a gradient problem, I am more concerned about understanding what the question is asking me.

    1. The problem statement, all variables and given/known data

    I have two straight lines which represents the vertical profile of a road.

    Line AB has a gradient of 1 in 169 (for every 1 unit in the Y axis, you move 169 units in the X axis)

    Line BC has a gradient of 1 in 410 (for every 1 unit in the Y axis, you move 410 units in the X axis)

    The question is, if the Change In Gradient between the two lines exceeds 1 in 500 then the road must be re-designed.

    A. Do the gradients of lines AB & BC exceed 1 in 500 – YES / NO.
    B. What is the change in gradient between Lines AB & BC.

    There are two parts of the question I am struggling to understand.
    • The first bit is understanding the change in statement.
    • The second bit is if the change in gradient is 1 in 600 for example then I would say that this is a shallower gradient and has not exceeded the 1 in 500 gradient threshold. If the change in gradient was 1 in 150 for example then this is a steeper gradient and has exceeded the 1 in 500 gradient threshold.

    2. Relevant equations


    3. The attempt at a solution

    From the statement “Change in” I would subtract the gradients of the two lines. So my first step would be:-

    1/169 – 1/410 = 410/69290 – 169/69290 (I found a common denominator)

    410/69290 – 169/69290 = 241/69290 (subtracted 410 – 169)

    241/69290 = 1/ 287.5104 (rounded to 1 in 289)

    Answer To Part A = YES the gradients has exceeded 1 in 500
    Answer To Part B = The change in gradient is 1 in 289.

    Is my thinking correct or have I got it wrong.

    Any help will be greatly appreciated.

    I have attached a sketch of the problem.


    Attached Files:

  2. jcsd
  3. Oct 14, 2013 #2
    I believe you have the right idea. However, for part A of the question I am not sure if they are asking you to determine if the gradient of AB and BC combined (AC) would 1/500 or if they are considering the individual lines. Either way, I believe you have to right answer.
  4. Oct 14, 2013 #3


    User Avatar
    Homework Helper

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

Have something to add?
Draft saved Draft deleted