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: Force Problem

  1. Apr 14, 2010 #1
    1. The problem statement, all variables and given/known data
    Mike is dragging a 20.0 kg crate across the floor. If he exerts 40 N force upon the crate and there is a 25 N frictional force opposing the crate's motion, how fast will the crate be moving after 2.0 seconds if it is initially at rest?


    2. Relevant equations
    FNET=ma


    3. The attempt at a solution
    I used FNET=ma to solve for the acceleration as follows:
    FPC-FFC=ma
    40-25=20a
    15=20a
    a=0.75m/s2

    Then here's where I'm not sure if this is correct: I multiplied the acceleration 0.75m/s2 by 2.0 seconds to get 1.5m/s2.
    Is this the correct answer for the question: How fast will the crate be moving after 2.0 seconds?
    Thanks.
     
  2. jcsd
  3. Apr 14, 2010 #2
    Almost right. What happens when you multiply an acceleration by a time? What are the units? (You have the correct numeric answer, your units are off)
     
  4. Apr 14, 2010 #3
    Oh it wouldn't be squared. So it would be 1.5m/s.
     
  5. Apr 14, 2010 #4
    Exactly.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook