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Homework Help: Tension and force question!

  1. Apr 11, 2005 #1
    After an incident over the mid-semester break involving a packet of Maltesers, a flooded creek,
    and a wombat, a 15,000 kg salvage helicopter is lifting a 4,500 kg truck with an upward
    acceleration of 1.4 m.s-2. Calculate:
    1) The force the air exerts on the helicopter blades.
    2) The tension in the cable between the truck and the helicopter

    1. F = ma, so we know the mass is (15000 + 4500)

    and would the acceleration be (9.8 + 1.4)?

    2. Would T = m1*g + m1a?
  2. jcsd
  3. Apr 11, 2005 #2
    The accelerations are in opposite directions. If you define the direction up as positive then g = -9.8 m/s^2.
  4. Apr 11, 2005 #3
    Yes, but will the 1.4 be negative as well because the overall acceleration should be greater than 9.8?
  5. Apr 11, 2005 #4
    No, the acceleration is what it is: 1.4m/s^2. You can take the upward direction as positive, so any downward pointing force is negative, and any upward pointing force is positive.
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