Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Please help w/ homework question, for my class tonight

  1. Sep 4, 2003 #1
    I am having a problem with two questions for my homework assignment.

    1st question:

    A force of 1 N acts on a mass of 1kg for a time of 1 s. (A)What is the acceleration of the mass? (B)What speed does the mass reach? (C)How far does the mass move?

    Here is my answer but I think it is wrong:
    (A) acceleration=1N/1kg = or 1 meter per second per second
    (B) acceleration=change in velocity/time.....I am not sure if that is the right equation to use
    (C) velocity=change in average position/elapsed time ?

    Then the second question that baffled me was:
    in terms of power, explain why roads going up mountains are full of switchbacks and hairpin turn?

    Is it something to do with the rate at which energy changes from on form to another?

    I am really confused! Please help.
  2. jcsd
  3. Sep 4, 2003 #2
    This one is good.

    Try. What do you have to lose?

    Regarding the second question: it's much harder (you need more power) to climb a steeper hill so given a mountain you build roads with a reasonable angle. At that angle you would need a longer mountain so you must make those sharp turns to keep the road on the mountain.
  4. Sep 4, 2003 #3


    User Avatar
    Science Advisor

    Sonty is completely correct.

    In regards to the road, remember that "energy is conserved". Go up a particular distance requires fixed amount of work (mg times height moved) but since work= force times distance, if you go a longer distance you can do the same work using less force.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook