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!

Unbanked Curve increasing speed

  1. Mar 17, 2015 #1
    1. The problem statement, all variables and given/known data

    A race car going around a flat, unbanked circular track gradually increases speed as it
    completes one full trip around the track. Which of the following can explain why the car gains
    speed?
    (A)
    Energy stored in the fuel is converted to mechanical energy.
    (B)
    A component of the frictional force exerted by the ground on the tires is directed toward
    the center of the circle.
    (C)
    A component of the frictional force exerted by the ground on the tires is in the direction of
    motion.
    (D)
    The car’s velocity and acceleration are perpendicular.

    2. Relevant equations


    (This is multiple correct so multiple answers may be correct)
    Just common sense

    3. The attempt at a solution

    So A is very obvious, but I'm not sure what else is correct because A is not the only one that's correct.
     
  2. jcsd
  3. Mar 17, 2015 #2

    andrewkirk

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Note that they use the word speed rather than velocity, and velocity is speed with a direction. Some of B,C,D are about changes in direction and hence affect velocity but not speed. To increase the speed of an object it needs to be pushed in the same direction as it is already moving. Think about Newton's third law of motion and what a car pushes on (that's not part of the car) to make itself go faster.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Unbanked Curve increasing speed
  1. Car on unbanked curve (Replies: 1)

  2. Unbanked curve problem (Replies: 6)

Loading...