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: Tangential Force

  1. Feb 19, 2008 #1
    In Uniform circular motion, the centripital acceleration is the inward force that keeps a particle on a circular track. My question is what exactly is the tangential force? Is it a fictious force? My first inclination is that is equal in magnitude to the centripital force but acts perpendicularly (sort of like the normal force). Is this reasoning correct? Someone please let me know, thanks.
  2. jcsd
  3. Feb 19, 2008 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    The tangential force is not a ficticous force; however, just because a particle undergoes circular motion doesn't nesscarily mean that there is a tangential force acting. A tangential force is often referred to as a torque and causes angular accleration, that is an applied torque increases that angular velocity of the rotating body.

    See http://hyperphysics.phy-astr.gsu.edu/HBASE/circ.html#rotcon" for more information on rotation concepts.
    Last edited by a moderator: Apr 23, 2017
  4. Feb 19, 2008 #3
    Then how does it apply to this problem:

    A 7.83 kg toy car is going around a circular track of radius 52.5 m at a constant speed of 17.3 m/s. Find:

    - the time it takes for the car to go around the track once

    - the magnitude of the inward force needed to keep it moving in a circle

    b) The same 7.83 kg toy car now starts at rest on the same track, and accelerates at a constant rate to a final speed of 1.93 m/s in 9.02 seconds. At the instant it reaches its final speed, find:

    - the magnitude of the inward force needed to keep it moving in a circle:

    - the magnitude of the tangetial force:

    Part A was really trivial and I got the answers right on the first try. However, the tangential force thing has thrown me for a bit of loop. For the first answer of part B i think 1.68 N is the answer, but after careful review I think its the answer to question II part B. Is the tangential force a component of the inward force? Does anyone have a clue about this one?
  5. Feb 19, 2008 #4
    My intuition was correct. 1.68 N is the measure of the tangential force, calculated using the acceleration of the car over that particular arc length of the circle. 0.55 N is the measure of the centrifical force keeping the toy car on the circle.
  6. Mar 2, 2009 #5
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook