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: Sliding ice

  1. Aug 30, 2007 #1
    1. The problem statement, all variables and given/known data

    A block of ice with mass 2.00kg slides 0.750m down an inclined plane that slopes downward at an angle of 36.9degrees below the horizontal.

    f the block of ice starts from rest, what is its final speed? You can ignore friction.

    2. Relevant equations

    F=ma, trig equations.

    3. The attempt at a solution

    not really sure how to tackle this one.
    i have initial velocity of 0, angle, mass and distance, but i can't figure out how to tie it all together.

    should i be tackling it one dimension at a time? seeing as i know the vertical acceleration and angle?
  2. jcsd
  3. Aug 30, 2007 #2


    User Avatar
    Science Advisor
    Homework Helper

    Find the component of the downward force (weight) in the direction of the slope.
    Then just f=ma to get the acceleration and v^2 = u^2 + 2as to get final speed.

    Or from conservation of energy. Find the vertical distance equivalent to 0.75m at 36.9deg
    then use PE = mgh = KE = 1/2 mV^2
  4. Aug 30, 2007 #3
    sweet thanks heaps.
    used the conservation formula and got 2.97m/s which was correct.
  5. Aug 30, 2007 #4


    User Avatar
    Science Advisor
    Homework Helper

    My tip is to always use energy conservation if you can. It's a lot simpler than getting all the forces in the right directions and less prone to errors.
  6. Aug 30, 2007 #5
    I always use that work-energy equation. (Assuming that there's nothing like potential energy)

    I guess, energy conservation can sometimes put you in trouble.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook