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: Equations of Kinematics, including gravity

  1. Aug 26, 2015 #1
    1. The problem statement, all variables and given/known data
    A hot-air balloon is rising upward with a constant speed of 2.20 m/s. When the balloon is 3.30 m above the ground, the balloonist accidentally drops a compass over the side of the balloon. How much time elapses before the compass hits the ground?

    2. Relevant equations

    3. The attempt at a solution
    I just started taking Physics 1111 at college and never having taken physics in high school, I have no idea where to start. I assume you would use the knowledge that an object falls towards earth at 9.8 m/s^2... I just don't even know what equation of kinematics to plug this information into? Thank you for your help!!
  2. jcsd
  3. Aug 26, 2015 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    You can start by writing the eqs. of kinematics in section 2 of the template. There are only a handful.

    You want an equation which relates distance, time, and acceleration.
  4. Aug 26, 2015 #3
    Starting out, you will do yourself a favor by breaking the problem into parts that are easier to visualize and solve. In this case, what is a good first part of the path of the compass?
  5. Aug 26, 2015 #4


    User Avatar
    Homework Helper

    What is the initial position?
    What is the initial velocity?
    What is the constant acceleration?

    Remember that velocity can be described by:
    ##\int_{t_0}^t a(s) ds +v(t_0)= v(t)##
    and position can be described by:
    ##\int_{t_0}^t v(r) dr +p(t_0)= p(t)##.

    Is simple integration part of your toolkit? What are the equations of kinematics?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted