AAMC Physics Diagnostic # 46 (Static Friction)

[ihatebluescrubs]

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Heres the passage and question


I don't get how they determined the Maximum Static force. What what I understand, the Fstatic is the minimum amount of force someone needs to apply before the object moves. So then shouldn't we be using 1500 instead (from the table)?

 

[Dipraman]

The passage states that "During the experiment the force on the rope was steadily increased until the tires began to skid.....Once the tires started to skid, the dragging force was reduced to a minimum to maintain a steady speed."

You are saying why not use 1500 instead since it is the minimum amount of force applied. But the tire was not moving then. This could be like me pulling the tire with my bulky muscles with a force of 100N and we could log that into the table but that would not be of any help since the tire is still stationary.


It started moving when 7500N of force was applied. So that is the "minimum force" required to overcome static friction. Their explanation is worded kinda weird.

Hope this helps