Friction Physics Example 3

Follow the full solution, then compare it with the other examples linked below.

Example 3

medium
The coefficient of static friction between a box and the floor is μs=0.4\mu_s = 0.4. If the box weighs 98 N98 \text{ N}, what is the maximum static friction force?

Solution

  1. 1
    The normal force equals the weight on a flat surface: N=98 NN = 98 \text{ N}.
  2. 2
    Maximum static friction: fs,max⁡=μsN=0.4×98=39.2 Nf_{s,\max} = \mu_s N = 0.4 \times 98 = 39.2 \text{ N}

Answer

fs,max⁡=39.2 Nf_{s,\max} = 39.2 \text{ N}
Static friction prevents an object from starting to move. The maximum static friction force is the threshold force needed to set the object in motion.

About Friction

A contact force that opposes the relative motion or tendency of motion between two surfaces in contact.

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More Friction Examples

Example 1 medium

A [formula] box sits on a surface with a coefficient of kinetic friction [formula]. What force is ne

Example 2 hard

A [formula] block on a surface ([formula]) is pushed with [formula]. What is the acceleration?

Example 4 medium

A [formula] crate is pulled across a level floor at constant speed by a horizontal [formula] force.

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