ollyhulbert17 Posted February 9, 2011 Share Posted February 9, 2011 a sprinter accelerates from rest to a top speed with an acceleration whose magnitude is 3.8m/s2. after achieving top speed, he runs the remainder of the race without speeding up or slowing down. the total race is fifty metres long. if the total race is run in 7.88 s, how far does he run during the acceleration phase? Link to comment Share on other sites More sharing options...
michel123456 Posted February 9, 2011 Share Posted February 9, 2011 Looks like homework to me. I always take a sheet of paper,a pencil, and put the question into a small diagram, that helps a lot. Link to comment Share on other sites More sharing options...
ollyhulbert17 Posted February 9, 2011 Author Share Posted February 9, 2011 Looks like homework to me. I always take a sheet of paper,a pencil, and put the question into a small diagram, that helps a lot. yeeh i tried that, my teacher said the answer is found using quadratics. Link to comment Share on other sites More sharing options...
rktpro Posted February 9, 2011 Share Posted February 9, 2011 use all the equations of motion. Link to comment Share on other sites More sharing options...
michel123456 Posted February 9, 2011 Share Posted February 9, 2011 yeeh i tried that, (...). Obviously, that didn't help. where is your problem? 1. understanding the parameters of the question? 2. which equations to use? 3. or the resolution (the math)? Link to comment Share on other sites More sharing options...
imatfaal Posted February 9, 2011 Share Posted February 9, 2011 Perhaps you should write down the equations of motion that you know - and see how they apply to your question. Bear in mind that you might have a situation that has a period of uniform acceleration followed by a period of uniform velocity. Michel is 100% correct - draw a diagram Link to comment Share on other sites More sharing options...
michel123456 Posted February 10, 2011 Share Posted February 10, 2011 (edited) Perhaps you should write down the equations of motion that you know - and see how they apply to your question. (...) There will be something missing. That's the reason he has to draw a diagram first. He may understand why there is only one solution to the problem, and how to put that into equation. Edited February 10, 2011 by michel123456 Link to comment Share on other sites More sharing options...
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