DaddyFed is right, it would be all of them.
I believe the answer is two convex lenses. A compound microscope has two systems of lenses for greater magnification, the ocular, or eyepiece lens that one looks into and the objective lens, or the lens closest to the object. Both the ocular lens and the objective lens are convex lens.
<span>A free body diagram is a representation of how the forces that are acting on a point or particle interact. You place your point at the origin and then draw your forces.
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<span>Whatever the focus of the experiment is, plus any others factors that might influence the outcome of the experiment. If you are testing a new cancer drug, the experimental group and the control group must both be people with the same type of cancer, and both be a representative distribution of the population, all races, genders, ages, etc. You want the only difference in the two groups to be what you are studying, i.e. the effects of the drug.</span>
Velocity, direction, or both at the same time.