an accererlating force of 500N changes an object from 40 m/s to 60 m/s in a distance of 100m. the mass is 25 kg determine the force of friction acting opposite this force.
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Expert's answer
2011-10-25T08:06:23-0400
Let's mark the fricting force by F. Using the second Newton's law we obtain: 500-F = 25a (1) The average speed of an object is (60+40)/2 = 50 m/s. So, moving time T: T = 100/50 = 2 s. Let's find the acceleration of an object: a = (60-40)/T = 20/2 = 10 m/s^2. From (1) we obtain: F = 500-25a = 500-25*10 = 250 N. So, the friction force has value 250N.
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