Acceleration homework

  • Thread starter Justhelp
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  • #1
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Homework Statement



Ten seconds after starting from rest, a car with a mass of 1000kg is moving at 40m/s. The acceleration of the car is?

Homework Equations



F=ma or a=vf-vi/t

The Attempt at a Solution



I have m=1000kg
t=10s
d=40m/s

I am not sure if d is 40m/s though or is the force?
And with one of the formulas I picked I wouldn't be able to use 1000kg? I have a feeling that this problem requires two formulas.
 

Answers and Replies

  • #2
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40


d=40m/s

I am not sure if d is 40m/s though or is the force?
And with one of the formulas I picked I wouldn't be able to use 1000kg? I have a feeling that this problem requires two formulas.
Just note that d is velocity of the car. The usual sign for velocity is u or v, and d or s is commonly used for distance/displacement.

So now, your initial velocity is 0, as it started from rest. You also know the final velocity, and the time interval to attain this final velocity(assuming constant acceleration) So, finding the acceleration shouldn't be a problem if you use one of those relevant equations :wink: And yes, you don't necessarily need the mass here. It can be used to calculate the force, but that doesn't concern the question....
 
  • #3
Doc Al
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All that is required is the basic definition of acceleration, which is the second equation you listed under 'relevant equations'.
 
  • #4
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Ah ok. I dislike when there is extra information or too little, I know it's how they try to mess you up. It makes me nervous as well thinking that there may be a formula that I don't know. But should. It's easier with too little information though.

Thank you.
 

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