How to find final velocity?

  • #1

Homework Statement


An 9.30 kg body moving at 9.30 m/s begins to decelerates uniformly. After 9.30 s the body is 9.30 m from the location were it started to decelerate.
What is the final speed of the body 9.30 s after it started to decelerate?


Homework Equations


I'm not sure what equation to use.


The Attempt at a Solution


I'm not sure how to tackle this problem to find final velocity when I only have initial velocity, time, and distance. Help please!
 

Answers and Replies

  • #2
PhanthomJay
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You can use a couple of the kinematic equations, but there is a single simple kinematic equation for constant acceleration that relates initial velocity, final velocity, displacement, and time. Which one is that?
 
  • #3
Would that be the d=1/2(vf+vi)t ?
I wasn't given that equation on my handout but I looked it up.
 
  • #4
PhanthomJay
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Speed is the magnitude of the velocity. Yes, that is the right equation; solve it for V_f; the magnitude of V_f is its speed. Speed is not distance divided by time. Distance divided by time is average speed. You are looking for the instantaneous speed.
 

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