What is the Average Speed and Acceleration of a Car on a Straight Road?

In summary: For d): the time when the speedometer will read the average speed you calculated for part a) as the instantaneous speed. A and b are correct, assuming they meant miles per hour per second for b. C & d can both be solved using this equation:In summary, at 3.2 seconds after starting the car, the car has an average speed of 22.5 mi/hr and an acceleration of 14.1 mi/hr/sec.
  • #36
45 mi/hr = 0 + 9 mi/hr/sec times t
Solve for t??
 
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  • #37
t would be 5.
 
  • #38
Tonia said:
45 mi/hr = 0 + 9 mi/hr/sec times t
Solve for t??
What was the speed you calculated in part a)?
 
  • #39
22.5 mi/hr
 
  • #40
Tonia said:
22.5 mi/hr
Right. That is the speed you are told to use in answering part d).
 
  • #41
so t is 2.5 seconds and that's the answer to d.
 
  • #42
Tonia said:
so t is 2.5 seconds and that's the answer to d.
Yes.
 
  • #43
Okay. thanks for your help!
 
  • #44
Let me ask you one more question just to make sure: for problems a) and c), the answer is the same? 22.5mi/hr??
 
  • #45
Tonia said:
Let me ask you one more question just to make sure: for problems a) and c), the answer is the same? 22.5mi/hr??
Yes.
 
  • #46
Okay, thanks!
 

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