1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Impulse help!(3 problems)

  1. Oct 21, 2007 #1
    Okay, I was absent the day we did impulse at school, so now I'm confused as to how to do some of it. I just need to know how to set up the problems, I know that impulse=F[tex]\Delta[/tex]t and that F[tex]\Delta[/tex]t=m[tex]\Delta[/tex]v...but I don't know where to go after that.

    The first problem:
    Two children, totaling 200 kg, are traveling at 10 m/sec in a 100-kg bumper car during an amusement park ride. They deliberately collide with an empty second car, mass 100 kg, which is at rest. Afterwards, the car with the two children moves off at a speed of 4.0 m/sec. What is the final velocity of the empty car?

    The Second problem:
    James, a 65-kg skin diver, shoots a 2.0-kg spear with a speed of 15 m/sec at a fish which is darting past him. How fast does James recoil when the spear is initially released?

    The Third problem:
    On a hot summer day, Jack and Leon are fishing in their boat, when they decide to jump into the water to cool off. Jack, 45-kg, jumps off the front of the boat with a speed of 2 m/sec. While at the exact same moment, Leon, 90-kg, jumps out of the back of the boat at a speed of 4 m/sec. If the boat has a mass of 100 kg and was at rest prior to the two boys jumping off, what will be its velocity just after both boys have abandoned ship?
     
  2. jcsd
  3. Sep 23, 2008 #2
    to the find final velocity of empty cart....
    in the equation....let P the momentum
    P(initial)=P(final)
    MV1+ MV2 = MV1 + MV2
    300kg(10m/s)+0=300kg(4.0m/s)+100kgV2
    3000kg*m/s-4800kg*m/s=100kgV2
    20400kg*m/s=100kgV2
    ----------------------(divided by 100kg)
    100kg
    V2=204m/s(final velocity of the empty cart)
     
  4. Sep 23, 2008 #3
    opps...
    sorry
    i was wrong for multiplying of 300kg(10m/s)=3000kg*m/s not 30000kg*m/s
    and multiplying 300kg*m/s(4.0m/s)=1200kg*m/s not 4800kg*m/s
    V2=8.82m/s
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Impulse help!(3 problems)
  1. HELP Impulse problem (Replies: 2)

Loading...