By integration. This means the plane is divided into small pieces, and the contribution of each individual piece to the moment of inertia is evaluated. There are mathematical methods to do this more or less easily - systematically, at least - for certain simple figures, and you can find the moment of inertial of many common figures published in lists.
find the strength of the member subject to bending or shear. Moment of inertia is used to find radius of gyratia or flexural regidity so that member strength flexural stress is found
length x width
you count the number of boxes IN the shape.
Yes, if it is bound by plane figures, just add the area of each plane figure. If it has a curved surface, divide it into many small pieces, to approximate the area with small rectangles or triangles, then add them up.
There is no such formula. To determine the area of an irregular plane shape split it into known shapes such as rectangles, triangles, segments of a circle etc. Determine the area(s) of each of these and sum the results to find the total area.
Comparing linear and circular motion we can see that moment of inertia represents mass and torque represents force. So the product change in the circular momentum per unit time is torque. Circular momentum is the product of moment of inertia and circular velocity.
Area of plane figure
The answer will depend on whether the axis isthrough the centre of the disk and perpendicular to its plane,a diameter of the disk, orsome other axis.Unless that information is provided, the answer is meaningless.
its used to find the moment of inertia of complex bodes like airplanes
In physics, the perpendicular axis theorem (or plane figure theorem) can be used to determine the moment of inertia of a rigid object that lies entirely within a plane, about an axis perpendicular to the plane, given the moments of inertia of the object about two perpendicular axes lying within the plane. The axes must all pass through a single point in the plane.Define perpendicular axes , , and (which meet at origin ) so that the body lies in the plane, and the axis is perpendicular to the plane of the body. Let Ix, Iy and Iz be moments of inertia about axis x, y, z respectively, the perpendicular axis theorem states that[1]This rule can be applied with the parallel axis theorem and the stretch rule to find moments of inertia for a variety of shapes.If a planar object (or prism, by the stretch rule) has rotational symmetry such that and are equal, then the perpendicular axes theorem provides the useful relationship:DerivationWorking in Cartesian co-ordinates, the moment of inertia of the planar body about the axis is given by[2]: On the plane, , so these two terms are the moments of inertia about the and axes respectively, giving the perpendicular axis theorem.
find the strength of the member subject to bending or shear. Moment of inertia is used to find radius of gyratia or flexural regidity so that member strength flexural stress is found
As with many other physical quantities, you need to use integration.
Along the height it is hb^3/48 and along base it is bh^3/36
In physics, the perpendicular axis theorem (or plane figure theorem) can be used to determine the moment of inertia of a rigid object that lies entirely within a plane, about an axis perpendicular to the plane, given the moments of inertia of the object about two perpendicular axes lying within the plane. The axes must all pass through a single point in the plane.Define perpendicular axes , , and (which meet at origin ) so that the body lies in the plane, and the axis is perpendicular to the plane of the body. Let Ix, Iy and Iz be moments of inertia about axis x, y, z respectively, the perpendicular axis theorem states that[1]This rule can be applied with the parallel axis theorem and the stretch rule to find moments of inertia for a variety of shapes.If a planar object (or prism, by the stretch rule) has rotational symmetry such that and are equal, then the perpendicular axes theorem provides the useful relationship:
metre4
-find the area(A) of the shape above the neutral axis (or above a particular point if given) - locate the centroid (y')of the shape relative to the neutral axis(or above point) using y' = ∑AiYi / ∑Ai - first moment of area = A*y' (or y' + distance of given point from neutral axis)
length x width