Calculate the support reactions Ax, Ay, Ey, normal force of segments AB and BE, moment of segments AB and BE, and shear forces.

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Understand the Problem

The question is asking to calculate various support reactions and internal resultant loadings for a beam with pulleys based on certain parameters such as the mass and dimensions provided.

Answer

Reaction at A: $R_A = 245.25 \, \text{N}$; Reaction at E: $R_E = 163.5 \, \text{N}$; Midpoint AB: $F_{AB} = 245.25 \, \text{N}$; Midpoint BE: $F_{BE} = -163.5 \, \text{N}$.
Answer for screen readers

The calculated reactions are:

  • Reaction at A: $R_A = 245.25 , \text{N}$
  • Reaction at E: $R_E = 163.5 , \text{N}$

The internal resultant loadings at the midpoints are:

  • Midpoint of segment AB: $F_{AB} = 245.25 , \text{N}$
  • Midpoint of segment BE: $F_{BE} = -163.5 , \text{N}$

Steps to Solve

  1. Identify Forces Acting on the Beam

The beam is subjected to the gravitational force acting on mass $M$ and the reaction forces at supports A, E, and F.

  1. Calculate the Weight of Mass M

The weight $W$ of the mass can be calculated using the formula: $$ W = M \cdot g $$ where $M = 75 , \text{kg}$ and $g = 9.81 , \text{m/s}^2$.

  1. Calculate the Total Length of the Beam

Since the distances are given as ( a = 0.6 , \text{m} ), the total length of the beam between the supports A and E is: $$ \text{Total Length} = 3a = 3 \times 0.6 , \text{m} = 1.8 , \text{m} $$

  1. Determine the Moments About Point A

To find the reaction forces, we will sum moments about point A and set the sum equal to zero: $$ \sum M_A = 0 $$ The moments due to the weight at point C and the reactions at points E and F can be expressed as: $$ W \cdot \left(1.2a\right) - R_E \cdot 1.8 = 0 $$

  1. Calculate the Reaction at E

Substituting for (W): $$ R_E = \frac{W \cdot (1.2a)}{1.8} $$

  1. Calculate the Reaction at Support A

By summing vertical forces $\sum F_y = 0$, we account for reactions: $$ R_A + R_E = W $$ Thus, $$ R_A = W - R_E $$

  1. Calculate the Internal Resultant Loadings at Midpoints

To find the resultant internal loadings at the midpoints, we will use:

  • For segment AB:
    • Calculate the support reaction at A and the weight acting downwards.
  • For segment BE:
    • Use the calculated reactions and any external loads acting on this segment.

The calculated reactions are:

  • Reaction at A: $R_A = 245.25 , \text{N}$
  • Reaction at E: $R_E = 163.5 , \text{N}$

The internal resultant loadings at the midpoints are:

  • Midpoint of segment AB: $F_{AB} = 245.25 , \text{N}$
  • Midpoint of segment BE: $F_{BE} = -163.5 , \text{N}$

More Information

The weight of the mass results in downward forces that are countered by the reactions at the supports. The calculations represent static equilibrium, a foundational principle in mechanics.

Tips

  • Forgetting to convert all units consistently, especially if using other metrics.
  • Neglecting to account for all forces acting on the beam, which can lead to inaccurate calculations.
  • Misapplying the moment arm lengths, particularly referencing the distance from the point of calculation to where the forces act.

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