I'm A Beginner! Need help! -9th Grade Physics-

  • Thread starter 1mai28
  • Start date
  • #1
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1. Homework Statement :

A dragster accelerates from rest at 49 m/s^2. How fast is it going when it has traveled 325 m?



I'm a complete beginner, I'm not really sure how to even approach this problem so please, with each step taken, provide a VERY detailed explanation of why and how you did this step! I'm so confused!
 

Answers and Replies

  • #2
537
1
we can't actually take you step by step through the problem here, but can try to help along the way

do you have any formulas regarding constant acceleration?
 
  • #3
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There is one kinematics equation that has everything you need to solve for final velocity.
 
  • #4
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Well so far, the formulas I've learned are:

v= Δx/t
a= Δv/t
Xf= X0 + V0t
Xf = X0 + V0t + 1/2at^2
Vf = V0 + at
Vf^2 = V0^2 + 2aΔx
 
  • #5
537
1
so if you look at those formulas and look at the information you've been given, and then look at what you need to find

which formula should you use
 
  • #6
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Umm, well the question is asking how fast it is going...

So I would have to use

Vf = V0 + at
or
Vf^2 = V0^2 + 2aΔx?

Or does it not matter which one I use?
 
  • #7
537
1
you aren't given anything about the time, so the first one is not going to be useful

so how would you use the equation you've chosen?
 
  • #8
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"A dragster accelerates from rest at 49 m/s^2. How fast is it going when it has traveled 325 m?"

So, Vf^2 = V0^2 + 2aΔx

I guess
a=49 m/s^2
Δx would be 325?
And its at rest? Would V0^2 be equal to 0 then?

So then,

Vf^2 = 0 + 2(49)Δ(325)?
 
  • #9
537
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yes :)

the key to these problems is listing what you know and what you don't know

then find the formula best suited for what you've got
 
  • #10
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So

Vf^2 = 31850?

Vf = 178.47?
 
  • #11
537
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looks good to me
 
  • #12
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Thanks! :D
 

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