So, then the same procedure I need to use for inertial force z, I will fix z then vary all the other way, all the substitute the values for other variables. Then I can get F I equal to q 1 into cos theta. Of course, this will be (No audio from: 38:41 to 38:47) an absolute value. R 1 into absolute of sin theta into sin theta, that may be the drag force and here it will be Q 1 into cos theta.