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    i nid help in solving these problems.

    4. A satellite of mass of 500kg is at a position 100km above the earth (G=6.67x1024Nm2/kg2 me=5.98x1024 kg and re=6.37x106 m). If the period of the satellite is 86.3min, calculate
    c) the energy needed to escape from the 100km altitude.
    Answer 1.53x1010 J
    d) the energy needed to move the satellite to an altitude of 200km.
    Answer 2.33x108 J

    5. A cart with a mass of 500g and a spring bumper (K=500N/m) traveling with a velocity of 4m/s collides with another cart with a mass of 300g at rest. Assuming the collision is elastic determine
    c) the maximum elastic potential energy store in the spring
    Answer 1.5 J
    d) the minimum separation if the length of the spring bumper is 30cm.
    Answer 7.7 cm

    7. Two students of mass 60kg each standing on a cart with a mass of 40kg jump off the cart with a velocity of 6m/s relative to the cart. Assuming no friction calculate the velocity of the cart after both students have jumped off the cart.
    Answer 5.85 m/s
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    (Original post by jeongsuman)
    7. Two students of mass 60kg each standing on a cart with a mass of 40kg jump off the cart with a velocity of 6m/s relative to the cart. Assuming no friction calculate the velocity of the cart after both students have jumped off the cart.
    Answer 5.85 m/s
    I don't think the answer is 5.85m/s.

    The mass of the two students will be 120 Kg their momentum will be 120*6=720Ns

    The momentum of the cart will be equal and opposite.
    40v =720
    v=720/40 = 18m/s

    What number is the question?
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    (Original post by jeongsuman)
    (G=6.67x1024Nm2/kg2 me=5.98x1024 kg and re=6.37x106 m)
    Forgive me if I am wrong but isnt G the universal gravitational constant 6.67x10-11Nm²kg-2
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    (Original post by jeongsuman)
    i nid help in solving these problems.

    7. Two students of mass 60kg each standing on a cart with a mass of 40kg jump off the cart with a velocity of 6m/s relative to the cart. Assuming no friction calculate the velocity of the cart after both students have jumped off the cart.
    Answer 5.85 m/s
    Model the boys as 1 particle of m=120kg v=6/s
    I=m(v-u)
    I=120(6-0)
    I=720Ns

    For the cart:
    I=40v
    720=40v
    v=18m/s

    Since theres no initial momentum its just the same then yours. I am not going to pretend to be a mechanics expert though, so might not be right it does seem abit to easy though.
 
 
 
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Updated: November 23, 2005

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