160 likes | 875 Views
8.3 Applications to Physics and Engineering. In this section, we will discuss only one application of integral calculus to physics and engineering and this topic is: The Center of Mass of Planar Lamina.
E N D
8.3 Applications to Physicsand Engineering In this section, we will discuss only one application of integral calculus to physics and engineering and this topic is: The Center of Mass of Planar Lamina Consider a thin flat plate of material with uniform density called a planar laminar. We think of center of mass as its balancing point.
Centroid of a Plane Region Consider a flat plate with uniform density that occupies a region R of the plane A. y Moment of R about the y-axis: Moment of R about the x-axis: R x a b Mass of Plate = (Density)(Area) Centroid of R: Note: If a lamina has the shape of a region that has an axis of symmetry, then the center of mass must lie on that axis.
B.R lies between on the interval [a, b] where y Mass of R x a b Centroid of R:
Examples: 1) Find the centroid of the region bounded by the curves. Solutions: y x 1 e D I D I
2) Find the center of mass of a semicircular plate of radius r. y By principle of symmetry, center of mass must lie on the y-axis. x (-r, 0) (r, 0)
3) Find the centroid bounded by the given curves. Solutions: Points of intersection y (1, 3) x (-2,0)