A10,000-kg railroad car travels down the track at 30 m/s and hits a second stationary railroad car of 20,000 kg. the cars become coupled and continue traveling. calculate the final velocity of the cars.

10 m/s

Explanation:

The problem can be solved by using the law of conservation of momentum: the initial momentum has to be equal to the final momentum, so we can write the following

where

is the mass of the first car

is the initial velocity of the first car

is the mass of the second car

is the initial velocity of the second car

is the final velocity of the two combined cars after the collision

Re-arranging the equation and substituting the numbers, we find

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.