Direction of static friction for an object on a car that is in circular motion

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Static friction acts in the same direction as the centripetal force for an object on a truck in circular motion because it prevents slipping between surfaces. While friction typically resists motion, it can also provide the necessary inward force to keep an object moving in a circle. Without friction, the object would slide outward due to inertia. Friction resists relative motion, allowing it to exert an inward force that accelerates the object toward the center of the circular path. Understanding this dual role of friction clarifies its importance in circular motion dynamics.
miri144
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Can someone please explain why static friction points in the same direction as the centripetal force for an object (like a box) on the flatbed of the truck that is traveling in uniform circular motion?

Thanks in advance. :)
 
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Well, the friction is what's applying the force to accelerate the object. So if the object is centripetally accelerating, then the friction is applying a centripetal force.
 
But I thought friction was supposed to resist motion, not accelerate objects.
 
miri144 said:
But I thought friction was supposed to resist motion, not accelerate objects.
Why can't it do both? Friction resists slipping between surfaces. If there were no friction, the object would tend to slide outward. Friction prevents that slipping and in the process exerts an inward accelerating force which keeps the object moving in a circle.
 
miri144 said:
But I thought friction was supposed to resist motion.
To reword Doc Al's post, friction resists relative motion between surfaces in contact with each other. The surfaces may be accelerating or experiencing an external force (such as gravity on an inclined surface), but if there is sufficient friction, there won't be any relative motion between the surfaces.
 

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