HESI A2 Exam: Friction
• What are the two main frictional forces?
• A force between two surfaces that prevents those surfaces from sliding or slipping across each other is __________
• Give an example of kinetic friction.
• Arrange the forces of rolling, static, and sliding friction in increasing order
Friction is a surface force that opposes relative motion. The two main frictional forces that you need to be familiar with are static and kinetic friction.
Friction is involved in helping a moving car to brake, keeping a runner from slipping, and even is needed when writing.
Static friction is a force between two surfaces that prevents those surfaces from sliding or slipping across each other. A form of static friction would be when your planted foot can grip the ground and push backward.
Kinetic friction always opposes the sliding motion and tries to reduce the speed at which the surfaces slide across each other. If you think of a baseball player sliding into a base, that is kinetic friction slowing him or her down.
Static friction is directly proportional to the normal force, and it increases until the object begins to move. Kinetic friction is a constant, and it is less than or sometimes nearly equal to the maximum static friction.
Rolling friction must always be less than sliding friction, because in order for an object to roll, the force of friction between it and the surface must be large enough to keep the object from sliding.
Static friction is more than sliding friction because the body needs to overcome the inertia of rest in static friction. In case of sliding friction, the body possesses inertia of motion since the body is already in motion.
A horse is harnessed to a cart. If it exerts a force on the cart, then based on Newton's Third Law of Motion the cart must exert an equal and opposite force on the horse. For the horse to move with constant velocity, the frictional force acting on it (the horse) as well as the mechanical force it applies on the cart need to balance each other out. Therefore, the force applied by the horse balances the force of friction.
When a bicycle is in motion, friction exerted by the ground on the two wheels is such that it acts in the backward direction on the front wheel and in the forward direction on the rear wheel. The magnitude of the frictional force on the rear wheel can be greater than, less than or equal to that of the front wheel.
#hesi #hesia2 #hesia2exam #nursing #nursingschool #nursingexam #nursingstudent #futurenurse