I am having problems with this physics problem.(adsbygoogle = window.adsbygoogle || []).push({});

Starting from rest a 6.0 kg block slides 2.2m down a rough 30deg incline in 2.0s. find the change in mechanical energy due to friction. answer in J.

I know that change in mechanical energy is obtained by E=Ef-Eo or Wnc=(KEf+PEf)-(KEo-PEo) and I have used that but must be using the wrong #s.

The given values are easy to plug in but I am not sure on heights and velocities. the block travels down the incline 2.2 m which is only a height drop of 1.1m do I use 2.2 or 1.1m?, and I figure the velocity to be 2.2m/2.0s= 1.1 m/s ,but since the block starts at rest is my initial velocity is 0 and final 1.1 right and I have tried using 1.1 and 2.2 as starting heights and 0 as final height, but cannot get the right answer.

any help is appreciated

thanks

ken

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# Homework Help: ? on change in mechanical energy

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