Stack two books and starting tilting the bottom book - how far can you tilt it before the top book slides off? What's going on between the books up until that point, and what changes when the book starts sliding?
One of the most important forces we deal with every day but don't really think about is friction. Friction is the force between two surfaces that are in contact, and it always tries to prevent or oppose the motion between the surfaces. Friction is the reason that moving things eventually stop moving.
Why is friction so important? Sure, friction prevents your stuff from sliding off your desk or your chair from moving around. But friction is also what allows you to hold things and walk forwards, it allows cars to drive on a road, and pretty much everything that we're used to in everyday life.
If it's so important, why do we often see "ignore friction" in physics problems? We usually ignore friction for the same reason that we ignore air resistance (which is really just a type of friction) - it's an extra force that complicates things, so we study the motion caused by the other forces acting on an object first. But compared to air resistance, friction plays a bigger role in most physics problems and the equation for friction is much easier to work with.
In this lesson we'll learn about the two most common types of friction: static friction and kinetic friction. We'll also learn how the friction force depends on the coefficient of friction and the normal force.
Stack two books and starting tilting the bottom book - how far can you tilt it before the top book slides off? What's going on between the books up until that point, and what changes when the book starts sliding?
One of the most important forces we deal with every day but don't really think about is friction. Friction is the force between two surfaces that are in contact, and it always tries to prevent or oppose the motion between the surfaces. Friction is the reason that moving things eventually stop moving.
Why is friction so important? Sure, friction prevents your stuff from sliding off your desk or your chair from moving around. But friction is also what allows you to hold things and walk forwards, it allows cars to drive on a road, and pretty much everything that we're used to in everyday life.
If it's so important, why do we often see "ignore friction" in physics problems? We usually ignore friction for the same reason that we ignore air resistance (which is really just a type of friction) - it's an extra force that complicates things, so we study the motion caused by the other forces acting on an object first. But compared to air resistance, friction plays a bigger role in most physics problems and the equation for friction is much easier to work with.
In this lesson we'll learn about the two most common types of friction: static friction and kinetic friction. We'll also learn how the friction force depends on the coefficient of friction and the normal force.
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