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Homework Help: Momentum Problems

  1. Jan 9, 2005 #1
    I need help with some momentum questions and the formulas i need to use to find the answers.

    1. A car weighting 15,680 N and moving at 20 m/s is actd upon by a 6.4 x 10^2 N force until it is brought to a halt.

    a. What is the car's mass? 1600Kg?
    b. What is its initial momentum?
    c. What is the change in car's momentum?
    d. How long does the braking force act on the car to bring it to a halt?

    2. A cannon on wheels fires a cannonball with a mass of 10 kg at a velocity of 20 m/s, horizontally. The cannon's recoil velocity is 1.5 m/s. What is the cannon's mass?

    3. A 35 g bullet moving at 475 m/s strikes a 2.5 kg wooden block. The bullet passes througgh the block , leaving at 275 m/s. The block was at rest when it was hit. How fast is it moving when the bullet leaves?

    4. Two campers dock a canoe. One camper steps onto the dock. This camper has a mass of 80 kg and moves forward at 4 m/s. With what speed and direction do the canoe and the other camper move if their combined mass is 110 kg?

    5. A 50 g projectile is launched with a horizontal velocity of 647 m/s from a 4.65 kg launcher moving at 2 m/s. What is the velocity of the launcher after the projectile is launched?

    6. A 6kg object, A, moving at velocity 3.0 m/s, collides with a 6.0 kg object, B, at rest. After the collision A moves off in a direction 40(degrees) to the left of its original direction. B moves off in a direction 50(degrees) to the righ tof A's original direction.

    a. Draw a vector diagram and determine the momenta of object and object B.
    b. What is the velocity of each object after the collision?
    Last edited: Jan 9, 2005
  2. jcsd
  3. Jan 9, 2005 #2
    we are not here to answer your hw, we are here helping you to understand physics, if you just want someone finish it for you , you come to a wrong forum. I will not answer your question unless you point out which part you do not understand....
  4. Jan 9, 2005 #3
    I'm not asking for the answers to my questions. What I'm asking is how to solve those individual questions. For example what formulas to use and if I should be converting from grams to kilograms. Well mostly on how to approach each question since I seem to be completly lost with momentun. I know that it seems I just copied all the questions I had but I've finished some that I understood already and this are the ones that I'm completly lost with.
    Last edited: Jan 9, 2005
  5. Jan 9, 2005 #4
    so surprise no one answer your question till now, usually people reply this types of question within 10 mins, let me give you some hints
    [tex]p(momentum)=m(mass)*v(velocity) (1)[/tex]
    [tex] \Delta p (change of momentum) = F(force)*t(time) (2)[/tex]
    [tex]F(force)=m(mass)*a(accelaration) (3)[/tex]
    and most important, the conservation of momentum (if you don't know what this is, go back to your text book and read, this is the most important part at your stage)

    1a, weight is a force which equal to [tex] mg [/tex], don't ask me what g is...
    1b, what is the formulas of momentum?
    1c, the car finally stop, which means its final momentum is......, and the change of momentum is just the different between final momentum and initial momentum
    1d, formulas (2) will help you in this case.

    2. use the conservation of momentum.

    3. use the conservation law again

    4,5 and 6, conservation, conservation,conservation.

    Ps. on question 5, change grams into kilograms.... 1kg=1000g
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