Question 392Deck General70% to pass
You are lifting a one-ton weight with a swinging boom. When comparing the stresses on the rig with the boom at 20° to the horizontal to the stresses when the boom is at 60° to the horizontal, which statement is TRUE?
AI Explanation
The correct answer is C) The stress on the head block is greater at 60°.
As the boom angle increases from 20° to 60° relative to the horizontal, the vertical component of the weight being lifted increases, resulting in greater stress on the head block. At 60°, the vertical force component is greater than at 20°, leading to higher stresses on the head block.
The other answer choices are incorrect because:
A) The thrust on the boom is actually greater at 60° due to the increased vertical force component.
B) The stress on the heel block would be lower at 60° as the horizontal force component decreases.
D) The angle of elevation does change the stresses in the masthead fairlead for the topping lift, as the vertical force component increases with a higher boom angle.
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