4.1.2. Basic Relations

Try these first

1. 1.

   What is the formula for stress?

   Hint

   Think about how much force is distributed over an area.

2. 2.

   When tension is considered a positive force, what is compression?

   Hint

   Remember the sign convention we discussed.

3. 3.

   What is the formula for calculating stress in a truss member?

   • Stress = P × A
   • Stress = P / A
   • Stress = A / P

   Hint

   Remember: stress is how much force is spread over an area.

4. 4.

   True or False: Tension forces are considered negative in the sign convention.

   • True
   • False

   Hint

   Think about our discussions on sign convention.

5. 5.

   A truss member undergoes a total axial load of 1000 N and has a diameter of 10 cm. Calculate the stress in the member and must decide if it's safe based on a material strength of 150 N/cm².

   Hint

   Apply the area formula first before finding the stress.

6. 6.

   A truss structure is subjected to external forces that cause moment reactions of 50Nm at the supports. If he member lengths are known, determine whether the truss is statically determinate by applying the criteria you've learned.

   Hint

   Refer back to the definitions of internal and external determinacy.