A 1542 kg car moving E @ 12 m/s strikes a 875 kg car moving S @ 17 m/s and the cars stick together. How do I find the direction and speed of the wreck immediately after the collision?
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kaciyoda
ANSWERS: 3
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Use the conservation of momentum. The sum of the momentums must be the same before and after, when you take into account the directions. momentum = mass * velocity so your working will look something like: m1 * v1 + m2 * v2 = (m1 + m2) * v3
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LOOK OUT!!!!!!, STOP!! ouch!...Is it ok to look? Is everyone OK? Are you sure? Just checking.
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When two objects like this stick together in physics we call this a completely inelastic collision. solve p=mv for both cars mv[car 1]=18504 kg*m/s mv[car 2]=14875 kg*m/s You can see right away which has the greater momentum, meaning that when the two cars come together they will continue more or less in that direction. Or you can add the vectors to obtain the direction. To find the speed after, solve P=mv for (v) v=P/m= (18504 kg*m/s + 14875 kg*m/s) / (1542kg + 875kg)= your answer. Note that the mass (kg) cancels leaving your answer in meters per second If you solve p(before) = mv[car 1] + mv[car 2] = p(after) = (m + m)v [car 1&2 combined] you must be careful to follow the sign convention, meaning the (+-) signs will take care of the two possible directions, but only for one dimensional motion.
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