Hi again, all. I thought of another question that I need help with. Again I have the answer but I'm not sure how they got to it. The question is:(adsbygoogle = window.adsbygoogle || []).push({});

A 1.6kg block is supported on a horizontal surface. The block is attached to a sping with k = 1000 N/m. The block compresses the spring x = 0.02 m and is then released from rest. The surface provides 4.00 N constant frictional force. Determine the speed of the block when located at spring's equilibrium point.

Now, I know to use W = (1/2)mv^2 - (1/2)mv^2 to find the velocity but I'm having trouble understanding how they got the total work. What they did was find the work done by the spring on the block and then find the work done by the friction and subtract the two to get the net work done.

But I tried to do it by calculating the spring force (which I got 20N for), subtract the friction so net force is 16 N and then multiply that by the distance 0.02 to get the net work done. But I get the wrong answer and I don't understand why. Maybe I am not calculating the spring force right? I'm using F = -kx.

Any help as to what I'm doing wrong would be greatly appreciated!

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# Homework Help: Simple hooke's law question

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