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: Newton's Laws/Conservation of Momentum/Kinetic Energy

  1. Oct 11, 2011 #1
    Hello, I have a mid-term for Physical Science due on Wednesday. It's a 5 question take-home mid-term. Now I know these questions may be trivial to some of you, but I am in college purely for a business degree and have no use for physics. I'm primarily just looking to pass this course. Now, don't think that I don't pay attention in class, because I do. I am a student with a 3.7GPA but I just cannot comprehend the way my instructor is teaching this class.. Anyway, here are the questions. Help with them are greatly appreciated.

    1. A 2.5 kg bowling ball slides accross the floor with a velocity of 4.0 m/s. The bowling ball has a kinetic energy and momentum of: _______ Joules and ________ kg*m/s

    2. If you were to lift the same bowling ball to a height of 4 m above the floor, its potential energy would increase by _______ Joules

    3. A freight train rolls along a track with a speed of 10 m/s. If it's speed were increased to 30 m/s, its kinetic energy would be increased by a factor of _______

    4. A 100,000kg railroad car traveling at 5 m/s collides with a stationary railroad car of the same mass. If the two cars couple together after the collision, because momentum will be conserved, they will have a speed of ________ m/s

    5. The acceleration of gravity at the surface of the earth is 9.8 m/s^2. If the mass of the earth could be doubled keeping its radius the same, the acceleration of gravity would then be _________ m/s^2

    2. Relevant equations

    If I knew, I probably wouldn't be asking..

    3. The attempt at a solution

    Once again, if I even knew were to begin, I might have an idea of what these solutions will be.

    I am not here for an easy 100.. I would like to be able to understand what is taught. If someone could explain these questions to me in a means in which I would be able to understand, I would appreciate it very much. Time is limited, my exam is due 6PM Tomorrow CST. Thank you for your time, understanding, and help!
  2. jcsd
  3. Oct 11, 2011 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    I believe that it's against our rules to help you with this take-home test.
  4. Oct 11, 2011 #3
    What is the point of homework help if it's against the rules to help with homework? That's a puzzling concept.. Oh well..
  5. Oct 11, 2011 #4
    re 1.Try to find the formulae for kinetic energy and momentum.
    re 2. Try using conservation of energy principle.
    re 3. use formula of KE
    re 4. use conservation of momentum.
  6. Oct 11, 2011 #5


    User Avatar

    Staff: Mentor

    Re-read the Rules link at the top of the page. You agreed to those rules when you joined the PF. The Homework Help rules are quite clear.

    This additional thread will help you understand why we have the HH rules that we do.


    This thread is locked. Do not post exam questions here in the future.

    PF Mentor
    Last edited: Oct 11, 2011
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook