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Zorluk: KolayFriction and Resistance

A technician is modifying a heavy steel sliding door that currently drags directly along a flat metal base. To significantly reduce the frictional resistance required to open and close the door, which of the following design changes would be the most effective?

  1. Incorporating steel ball bearings or roller wheels between the door and the base.Cevap
  2. B
    Widening the base track so the door's weight is distributed over a larger surface area.
  3. C
    Increasing the total mass of the door so it carries more momentum once pushed.
  4. D
    Decreasing the pushing speed to minimize the reaction force from the track.

Cevap

Incorporating steel ball bearings or roller wheels between the door and the base.
The correct answer identifies that converting sliding friction into rolling friction (by using wheels or bearings) is one of the most effective mechanical methods to reduce resistance. Rolling friction is generally much weaker than sliding friction because the contact surfaces do not grind against each other as they move.

Adım Adım Çözüm

1
Identify the type of friction currently acting on the door.
The door dragging flat against a metal track experiences kinetic (sliding) friction.
Understanding the current state helps identify how to improve the system.
2
Evaluate the options based on mechanical principles to find the best method for reducing resistance.
Adding wheels or ball bearings changes the interaction from sliding to rolling.
Rolling friction is significantly lower than sliding friction for hard materials like steel, making this the most effective mechanical improvement.

Anahtar Kavram

Rolling friction is substantially lower than sliding (kinetic) friction, which is why wheels and bearings are used in mechanical designs to reduce resistance.
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Friction and Resistance

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