Bennett Mechanical Test Structures and Center of Gravity 3 — Questions and Answers
Question 1: A triangular shelf bracket transfers a load to the wall. Which member is typically in compression?
- The diagonal brace (Correct answer)
- The screw heads
- The wall paint
- None of them
Correct answer: The diagonal brace
The diagonal brace pushes against the wall and is loaded in compression.
Question 2: Where is the center of gravity of a uniform L-shaped flat plate?
- Outside the material of the L (Correct answer)
- At the inner corner
- At the longest tip
- At the exact midpoint of one arm
Correct answer: Outside the material of the L
For an L-shape, the center of gravity falls in the empty region between the arms, outside the material.
Question 3: A loaded wheelbarrow is easier to lift when the load is placed where relative to the wheel?
- Directly over the wheel (Correct answer)
- Far behind near the handles
- On the handles
- It makes no difference
Correct answer: Directly over the wheel
Placing the load over the wheel lets the wheel bear most of the weight, reducing lifting effort.
Question 4: A balanced see-saw has a 40 lb child 4 ft from the pivot. Where must a 20 lb child sit to balance?
- 8 ft from the pivot (Correct answer)
- 4 ft from the pivot
- 2 ft from the pivot
- 1 ft from the pivot
Correct answer: 8 ft from the pivot
Balance needs equal moments: 40x4 = 20x8, so the lighter child sits 8 ft out.
Question 5: A flat tabletop rests on four legs. The combined center of gravity of the table is best described as?
- Above the center of the tabletop (Correct answer)
- At one corner leg
- Below the floor
- Outside the table
Correct answer: Above the center of the tabletop
A symmetric table has its center of gravity centered above the middle of the top.
Question 6: When stacking irregular rocks into a stable cairn, you should place the heaviest rocks where?
- At the base (Correct answer)
- At the very top
- Balanced on edges
- Randomly
Correct answer: At the base
Heaviest rocks at the base keep the center of gravity low for stability.
Question 7: A bridge arch carries load primarily through which type of internal force?
- Compression (Correct answer)
- Tension
- Twisting only
- No force
Correct answer: Compression
An arch carries its load mainly in compression along its curve.
Bennett Mechanical Test Structures and Center of Gravity 3
A triangular shelf bracket transfers a load to the wall.
Which member is typically in compression?