Recent content by rueberry

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    Calculating Work to Stop a 1000 kg Car at 100 km/hr

    When I work that problem out, I get 383645J, but the answer in the book says 386,000J. Am I doing something wrong? If I use 27.7 m/sec in the equation, I get 1/2(1000kg)(27.7m/sec)=383645
  2. R

    Calculating Work to Stop a 1000 kg Car at 100 km/hr

    How much work is required to stop a 1000 kg car traveling at 100 km/hr? I was going to use KE=1/2mv^2 , since the work should equal the KE, assuming no friction. I have: =1/2(1000 kg)(100km/hr)^2 I was using dimensional analysis to make the conversion to m/s, so I end up with J, but...
  3. R

    Can the KE of a car be converted into work by stopping it at 100 km/hr?

    Then maybe I'm not setting up the conversion correctly, I was using dimensional analysis and set it up (100 km/hr) (1000m) (3600 sec) = 3.6 x 10^8 (1 km) (1 hr) but I know this is wrong, by the time you square it and finish the equation, its way too...
  4. R

    Can the KE of a car be converted into work by stopping it at 100 km/hr?

    How much work is required to stop a 1000 kg car traveling at 100 km/hr? What I was thinking was that I would use the formula for KE, KE=1/2mv2 (last two of course is for squared since the KE would equal work. I have gotten as far as: KE= 1/2(1000 kg)(100km/hr)2 I am...
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    Solving Collision Between 120kg Tackler and 75kg Halfback

    I have been working on this for some time, maybe I'm just using the wrong formula. A 120 kg tackler traveling 3 m/sec tackles a 75 kg halfback running 6m/sec in the opposite direction. What is their common speed immediately after the collison? Thank you.
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