Afreight train car with a mass of 1.2 _ 104 kilograms, travelling with a velocity of 23 meters/second, collides with a stationary freight train car of equal mass. what is the momentum of the system after the collision?
a. 1.2 × 105 kilogram meters/second
b. 1.4 × 105 kilogram meters/second
c. 2.4 × 104 kilogram meters/second
d. 2.8 × 105 kilogram meters/second

c because the action was the roller coaster reaches bottom of hill (action) reaction would be blood tends to drain away from head

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the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.