University High School of Science and Engineering

• UHS 101

• Activity 2.1.2 Beam Deflection Introduction Engineers must look for better ways to build structures. Less material typically means that structures will be lighter and less expensive. Knowing the moment of inertia for different shapes is an important consideration for engineers as they strive to make designs lighter and less expensive. Equipment  1- 2x4 (preferably straight, free of knots and imperfections)  Dial calipers or a ruler with 1/32 divisions  2 - 1 foot lengths of 2x4 for use as supports  Tape measure  Permanent marker  Floor scale  Cinder block (Concrete Masonry Unit) Procedure You will determine the weight of one of your classmates using nothing more than a standard 2x4 and a measuring device. This activity will provide you with a better understanding of Moment of Inertia and how it can be used to determine the strength of beams. Preliminary lab calculations to determine beam Modulus of Elasticity 1. Calculate beam Moment of Inertia B – width of the beam (in.) h – height of the beam (in.) I – Moment of Inertia (in.4 ) Vertical Orientation Horizontal Orientation I = B=1.5 H=3.5 Bh^3/12 =5.359in^4 I = B=3.5 H=1.5 Bh^3/12 =0.984in^4 Position the beam as shown below