[End Apps] Beam Deflection

Beam A and B are the same material and same dimensions. What distinguishes beam A from beam B?

• Beam A will have a greater resistance to bending because it has a lower moment of inertia.

• Beam A will have a greater resistance to bending because it has a higher moment of inertia.

• Beam B will have a greater resistance to bending because it has a lower moment of inertia.

• Beam B will have a greater resistance to bending because it has a higher moment of inertia.

What does the Moment of Inertia describe?

• An objects stiffness related to its shape

• An objects stiffness related to its chemical properties

• An objects rotation because of inertia

• An objects rotation because of force

What units is Moment of Inertia measured in?

• in⁴

• psi

• in²

• lbf

Why does a beam's orientation change it's Moment of Inertia? (Choose the BEST option)

• You are changing what the measured Height is, which heavily impacts Inertia Calculations

• You are changing the measured Base, which heavily impacts Inertia Calculations

• You are changing the beam's length, which heavily impacts Inertia Calculations

• Beam orientation doesn't matter, the Moment of Inertia stays the same.

The ratio of stress and strain is called the...

• plastic deformation

• ductility

• modulus of elasticity

• resistance to rupture

What does the Modulus of Elasticity describe?

• An objects stiffness based on its shape

• An objects stiffness based on its chemical properties

• An objects rotation because of inertia

• An objects rotation because of force

Correct formula for calculating beam deflection:

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• 
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Describe the relationship between the maximum beam deflection and the length of the beam. Are the two directly related? Inversely related? Not related?

• Directly Related: As the length of the beam increases, so does the maximum beam deflection.

• Inversely Related: As the length of the beam increases, the maximum beam deflection decreases, and vice versa.

• Not related

Given the information above, calculate the max beam deflection (δ_max) for Beam A:

• 0.12 inches

• 1.39 inches

• 0.53 inches

• 0.24 inches

Answer explanation

δ_max = (250 lb)(120 in)³/((48)(1,800,000 psi)(20.80 in⁴))

A force of 260 lb. is applied to the center of a 6 ⅙ feet long beam. The beam cross-section dimensions are 15.0 in x 1.3 in (W x H) and has a modulus of elasticity of 3.64 x 10⁶ psi.

Calculate the moment of inertia (I).

• 2.75 in⁴

• 365.63 in⁴

• 27.5 in³

• 3.66 in⁴

Answer explanation

I = (15 in)(1.3 in)³/12