The Machines
Screw
A screw is a common household device used to fasten two objects together with binding force. A screw not only holds better than a nail, but it requires less force to drive. The threads, or the spiral-shaped protrusions that come out from the main body of the screw help you to accomplish this task. This is a picture of your basic household screw:
A Screw.
Drawing Analysis:
- Green Arrow: This arrow represents the direction that the screw's force is applied to must pull to drive it into the object.
- Red Arrow: This is the resistance force provided by the object.
- Gray Shape: This represents the body of the screw.
- Black Lines: This represents the screw's threads.
The reason why a screw gives you a mechanical advantage is the threads. To show you why this advantage exists I will provide you with a model of a mountain. It is easier to drive in circles around the mountain to get to the top versus trying to go straight up. Although the straight up path is shorter it requires less force to get up the mountain if you follow a spiral shaped path up around it, sort of like those parking garage ramps that make you feel sick.
Mechanical Advantage & Screws
The following problem is designed to test your skills of logical reasoning and deduction. It is okay if you don't know the answer.
When driving a screw into an object, do you use less force if you use a screw with more threads (a fine threaded screw) or less threads (a coarse screw)? Assume that the screw will be the same length in both scenarios.
Select the appropriate answer and hit the 'answer' button:
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