The density at any point on a semicircular lamina with diagonal placed on the x-axis with center on the origin is proportional to the distance from they-axis. Find the center of mass of the lamina.

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.

Suppose a wheel with a tire mounted on it is rotating at the constant rate of 2.15 times a second. a tack is stuck in the tire at a distance of 0.373 m from the rotation axis. noting that for every rotation the tack travels one circumference (a) find the tack's tangential speed. (b) what is the tacks radial acceleration?

What is an aquifer for science class