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Physics question

  1. Feb 3, 2009 #1
    1. The problem statement, all variables and given/known data

    1.the HARP(high altitude research project) gun can fire an 79 kg projectile containing scientific instrument straight up of 177 km, if we pretend there is no air resistance. what muzzle speed is required to attain this altitude?how long does the project remain at a height in excess of 1.00*10^2 km the height of interest for high-altitude research?

    2.an automobile speeding at 110 km/h passes a stationary police cruiser. the police officer starts to move her cruiser in pursuit 5 s after the automobile passes. she accelerate uniformly to 131 km/h in 7s and then continue at uniform speed until she catch the speeder.
    A)how far ahead relative to cruiser, is the speeder when the cruiser reaches the uniform speed of 131 km/h?
    B)how long does the police cruiser take to catch the speeder?
    c)how far from the initial position is the speeder caught?

    2. Relevant equations

    kinematic

    3. The attempt at a solution
    i need the answer and explanation
     
  2. jcsd
  3. Feb 3, 2009 #2
    For 1) what equations specifically do you think are pertinent? Write post what you have.

    For 2) Again write down the pertinent equations. Also draw a diagram here relating position and time. Helpers may not be able to see your picture but you may see what is happening more easily.
     
  4. Feb 3, 2009 #3
    for the first one use conservation of kinetic and potential energies

    2. idonno know how to draw the graph :S
     
  5. Feb 3, 2009 #4
    GOOD!

    Let's tackle question 1).

    How much energy is needed to get to maximum altitude?
    (Hint: use the potential energy equation.)
     
  6. Feb 3, 2009 #5
    GOOD!

    Let's tackle question 1).

    How much energy is needed to get to maximum altitude?
    (Hint: use the potential energy equation.)
     
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