7.5. Fundamental Equations of Statics

Try these first

1. 1.

   Define equilibrium in your own words.

   Hint

   Think about balance.

2. 2.

   What is meant by the sum of forces being zero?

   Hint

   Consider pushing and pulling in opposite directions.

3. 3.

   What is the first condition for static equilibrium?

   • \\(\\Sigma F_x \\neq 0\\)
   • \\(\\Sigma F_y = 0\\)
   • \\(\\Sigma F_x = 0\\) and \\(\\Sigma F_y = 0\\)

   Hint

   Think balance in both directions.

4. 4.

   True or False: Moments do not affect the stability of a structure.

   • True
   • False

   Hint

   Consider a seesaw with unequal weights.

5. 5.

   A beam is propped up at both ends with an 800 N weight placed 2 meters from the left support. Calculate the reactions at both supports.

   Hint

   Use the equilibrium of moments about one of the supports.

6. 6.

   A triangular truss has forces acting on two joints. If one joint has a downward force of 300 N, what must the other joint's upward force be for equilibrium?

   Hint

   Balance forces vertically.