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Homework Help: Grade 11 Physics Questions

  1. Nov 22, 2004 #1
    Just couple of of Physics questions. I want to make sure I got them right.

    1.How much force (tension must a rope withstand if it is used to accelerate a 1700 kg car at 0.50m/s^2 on a frictionless surface.
    I got:


    2.A 0.15kg baseball travelling at 35.0m/s strikes the catcher's mitt which recoils backwards 10 cm as it brings the ball to rest.
    A) What was the force applied by the ball on the glove?
    B) What was the force applied by the glove on the ball?
    I don't know how to do this one

    3.A parachutist is moving downward with a force due to gravity of 630N experience a a fricitonal air resistence of 450N.
    A)Calculate the acceleration of the parachutist.
    B)Calclation the acceleration of the block.







  2. jcsd
  3. Nov 22, 2004 #2
    I don't like the last two. For the third you are right up until F = MG where you for some reason assume the mass is variable with force as opposed to the acceleration. For #2, use the fact that [tex]v_f^2 = v_i^2 + 2ad[/tex] to find the acceleration. From there it's trivial to find the force.
  4. Nov 22, 2004 #3
    What do you mean you don't like them??

    Anyway Raza, for question 2(b) you need to know Newton's Third Law: the magntiude force [tex]F_{AB}[/tex] on A due to B equals the magnitude of the force on B due to A, [tex]F_{BA}[/tex] and these forces are equal and opposite:

    [tex]\vec{F_{AB}} = -\vec{F_{BA}}[/tex]

    Hope that helps.

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