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Friction and Newton's Laws

Part of the Mechanics section of Coddy's Physics journey. Lesson 15 of 94.

Friction is one more force in Newton's second law:

F - μN = ma

With no push, friction alone acts, so the object slows down.

A puck sliding right on ice, the arrow v showing which way: the only force along the ice is friction f to the left, and the acceleration a also points left

No push: friction alone acts along the ice, so a points against v, the way the puck moves, and it slows down.

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Challenge

You push a 10 kg crate to the right with 60 N, and it slides across the floor. The kinetic friction coefficient is μ = 0.4. Find its acceleration a.

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