Math Problem Statement

In a 10 feet cantilever beam, find the reactions if there are two forces, each 50lb, applied at a point 5 feet and 8 feet from the end of the beam with the support? Answer it completely and make an FBD make sure the FBD is like you draw in the paper not 3d just 2d

Solution

Here is the Free Body Diagram (FBD) for the cantilever beam with the applied forces and reactions as described.

2. Summing the Forces:

  • The sum of the vertical forces must be zero: ΣFy=Ry50lb50lb=0\Sigma F_y = R_y - 50 \, \text{lb} - 50 \, \text{lb} = 0 Ry=100lbR_y = 100 \, \text{lb} Thus, the vertical reaction at the fixed end is Ry=100lbR_y = 100 \, \text{lb}.

3. Summing the Moments about the Fixed End:

  • Take moments about the fixed end (assuming counterclockwise moments are positive): ΣM=0\Sigma M = 0 Moment due to the force at 5 feet: M1=50lb×5ft=250lb-ft(clockwise)M_1 = 50 \, \text{lb} \times 5 \, \text{ft} = 250 \, \text{lb-ft} \, \text{(clockwise)} Moment due to the force at 8 feet: M2=50lb×8ft=400lb-ft(clockwise)M_2 = 50 \, \text{lb} \times 8 \, \text{ft} = 400 \, \text{lb-ft} \, \text{(clockwise)} The total moment at the fixed end must balance these: M=M1+M2=250+400=650lb-ftM = M_1 + M_2 = 250 + 400 = 650 \, \text{lb-ft} Thus, the reaction moment at the fixed end is M=650lb-ftM = 650 \, \text{lb-ft}.

Final Reactions:

  • Vertical Reaction: Ry=100lbR_y = 100 \, \text{lb}
  • Moment Reaction: M=650lb-ftM = 650 \, \text{lb-ft}

Would you like any further clarifications on this?

Here are some related questions for better understanding:

  1. How does the location of the applied forces affect the moment at the fixed end?
  2. What happens to the reactions if the forces are moved closer to the fixed support?
  3. How would the reactions change if one of the forces were removed?
  4. What are the differences in reactions between a simply supported beam and a cantilever beam under the same loading conditions?
  5. How do distributed loads affect the calculation of moments and reactions in cantilever beams?

Tip: Always double-check the units when calculating moments to ensure they are consistent across all terms.

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Math Problem Analysis

Mathematical Concepts

Statics
Forces and Moments
Equilibrium of Structures

Formulas

Sum of forces: ΣF_y = 0
Sum of moments: ΣM = 0
Moment: M = Force × Distance

Theorems

Static Equilibrium

Suitable Grade Level

Undergraduate Engineering