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  1. Tonia

    Initially you are driving at 45 ft/sec on a straight road

    55.8 ft/sec - 45 ft/sec = 10.8 ft/sec 10.8ft/sec/6.30ft/sec^2 = 1.714 sec. = 1.7 seconds d) determine how much of the 300 ft displacement is due to the initial velocity and how much is due to the acceleration e) find the time required for traveling the first 150 ft.
  2. Tonia

    Calculate the Average speed

    Okay, thanks!
  3. Tonia

    Calculate the Average speed

    Let me ask you one more question just to make sure: for problems a) and c), the answer is the same? 22.5mi/hr??
  4. Tonia

    Calculate the Average speed

    Okay. thanks for your help!
  5. Tonia

    Calculate the Average speed

    so t is 2.5 seconds and that's the answer to d.
  6. Tonia

    Calculate the Average speed

    t would be 5.
  7. Tonia

    Calculate the Average speed

    45 mi/hr = 0 + 9 mi/hr/sec times t Solve for t??
  8. Tonia

    Initially you are driving at 45 ft/sec on a straight road

    (76ft/sec + 45 ft/sec.)/2 = 121/2 = 60.5 ft/ sec. 300 ft / 60.5 ft/ sec. = 4.9 seconds?? acceleration = m = a = change in velocity divided by change in time = (76ft/sec - 45 ft/sec)/4.9 sec. = 31ft/sec/4.9 sec. = 6.3 ft/sec^2 c) find the time when the speed of the car will be 55.8 ft/sec. ...
  9. Tonia

    Calculate the Average speed

    The equation would be Vf = Vo + at??
  10. Tonia

    Calculate the Average speed

    It would be the same?
  11. Tonia

    Calculate the Average speed

    Would the expression for speed be: v = m = (45 mi/hr - 0 mi/hr)/2.5 sec. = 18 mi/hr/sec.??
  12. Tonia

    Calculate the Average speed

    The graph would look like this: /
  13. Tonia

    Initially you are driving at 45 ft/sec on a straight road

    Homework Statement Initially you are driving at 45 ft/sec on a straight road. You accelerate the car at a steady rate and increase the speed to 76ft/sec. During this acceleration process you travel a distance of 300 ft. Homework Equations a) Calculate the time required for the 300 ft travel...
  14. Tonia

    Calculate the Average speed

    But the instantaneous speed appears to be the same number as the average speed, which is 22.5 mi/hr. Now what about: what about the time when the speedometer will read the average speed you calculated for part a) as the instantaneous speed??
  15. Tonia

    Calculate the Average speed

    Sorry, I meant that the accleration os 9 mi/hr/sec.
  16. Tonia

    Calculate the Average speed

    what about the time when the speedometer will read the average speed you calculated for part a) as the instantaneous speed??
  17. Tonia

    Calculate the Average speed

    So then, the average speed is the same as the acceleration and the same as the instantaneous speed? which is all 22.5 mi/hr??
  18. Tonia

    Calculate the Average speed

    So then it's 9 mi/hr/sec. times 2.5 seconds = 22.5 mi/hr??
  19. Tonia

    Show that Newton's 2nd Law is *Not* valid in a reference frame

    Homework Statement Show that Newton's Second Law is NOT valid in a reference frame moving past the laboratory frame of problem 1 with a constant acceleration? Problem 1: In a laboratory frame of reference, an observer notes that Newton's Second Law is valid. Show that it is also valid for an...
  20. Tonia

    Calculate the Average speed

    9 mi/hr/sec. times 2.5 seconds = 22.5 mi/hr because the seconds cancel?? So I get the instantaneous from multiplying the acceleration times the time? which would be 9 mi/hr/sec. times 5 seconds = 45 mi/hr?? I am confused.
  21. Tonia

    How far does it take for an object to reach maximum velocity

    A relative asked the question, he didn't give the weight or the air drag. Apparently, the question can't be answered unless I have those two pieces of information.
  22. Tonia

    How far does it take for an object to reach maximum velocity

    How does setting the equation equal to the object's weight tell me at what point air drag is equal to the weight??
  23. Tonia

    How far does it take for an object to reach maximum velocity

    Homework Statement At what distance (OR at what time) does it take for an object falling at 32 ft per sec per sec. to reach terminal velocity in its descent?? Homework Equations The only equation I can think of to use here would be distance = (rate of descent) times time. The Attempt at a...
  24. Tonia

    Calculate the Average speed

    So, for c): the speed of the car at t = 2.5 seconds = velocity = accel. times the time = 9 mi/hr/sec. times 2.5 seconds = 22.5 mi/hr/sec^2 and for d) it's the same answer?? How does speed equal the velocity which equals the acceleration times the time?? I don't get that.
  25. Tonia

    Calculate the Average speed

    a) the average speed during the 5 seconds b) the acceleration in miles per second at t = 3.2 sec. after you start your car = 9 mi/hr/sec?? c) the speed of the car at t = 2.5 sec. d) the time when the speedometer will read the average speed you calculated for part a) as the instantaneous speed.
  26. Tonia

    Calculate the Average speed

    Oh, so it's 45 mi/hr - 0mi/hr divided by 5 seconds? equals 9 mi/hr/sec acceleration?
  27. Tonia

    Calculate the Average speed

    So I just do this: (Vf - Vo)/t = 45 mi/hr divided by 3.2 seconds and I get 14.1 mi/hr/sec. which is the acceleration?
  28. Tonia

    Calculate the Average speed

    I want to understand how to solve this but I'm not sure what I need to do next.
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