Physics Help Forum Is this a constant or variable force?

 Kinematics and Dynamics Kinematics and Dynamics Physics Help Forum

 Apr 6th 2009, 06:40 AM #1 Junior Member   Join Date: Mar 2009 Posts: 9 Is this a constant or variable force? F(net) = (umg + 1/2*rho*A*v^2) If it is constant I can describe the work done as W = F(net)delta(r) If it varies I need to describe it as W(net) = integral from s0 to sf of (F(net).dr)
 Apr 9th 2009, 05:59 AM #2 Junior Member     Join Date: Mar 2009 Posts: 6 What is A? As F is function of $\displaystyle v^2$, and supposing that is not equal to zero, there will be an acceleration so v will change and so F.
 Apr 9th 2009, 09:03 AM #3 Physics Team   Join Date: Feb 2009 Posts: 1,425 You haven't specified what all the other terms are and the conditions under which this occurs. This looks like a combination of friction and drag. In general it looks like a variable force as v^2 is present. The net force can cause deceration and a slowing down which will affect F. However if there is some mechanism by which v is maintained constant, then F too will be a constant.

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