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Homework Help: Speed, velocity and accelaration

  1. Jun 17, 2004 #1
    Just need some help with the following questions which are probably very easy to you guys. Here are the 2 questions I need help with.

    1). A boat sails 150m due south and 150m due east. This takes a total time of 45s. Calculate (i). the boat's average speed and (ii) the boats average velocity.

    2). A car traveling at 10 ms -1 due north speeds up uniformly to a velocity of 25 ms-1 in 5 s. Calculate the acceleration of the car during these 5 seconds. Let the direction of the motion of the car, due north, be taken as the positive (+) direction.

    Thanks in advance.

    Billy. Can email me at: annaporcel@talk21.com
  2. jcsd
  3. Jun 17, 2004 #2


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    1) Average speed = Total Distance/Total Time = 300m/45s = 6.7m/s
    Average velocity = Total Displacement/Total Time = (150m[south] + 150m[east])/45s
    = 150[itex]\sqrt{2}[/itex]m[south-east]/45s = 4.7m/s[south-east]

    2) a = (v2 - v1)/t = (25 - 10)/5 = 3 m/s -2
  4. Jun 18, 2004 #3

    Thanks very much for your help. Much appreciated.
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