Suppose a child walks from the outer edge of a rotating merry-go round to the inside. Does the angular velocity of the merrygo-round increase, decrease, or remain the same? Explain your answer.
Forces of Friction - To slide one such surface across another requires a force larger enough to overcome the resistance of microscopic hills and valley bumping together. This is the origin of the force we call friction - When an object is in motion on a surface or through a viscous medium, there will be a resistance to the motion. - This is due to the interactions between the object and its environment. o This resistance is called the force of friction. - Force that slows down or stops motion. - Force that helps to start motion. - Problem-Solving Hints o Conceptualize Draw a diagram Choose a convenient coordinate system for each object o Categorize Is the model a particle in equilibrium If so, F = 0 Is the model a particle under a net force If so, = ma Kinetic friction - Is the friction encounter when surfaces slide against one another with a finite relative speed - Fk acts to oppose the sliding motion at the point of contact between the surfaces - The kinetic frictional force is also independent of the relative speed of the surfaces, and of their area of contact - The force of kinetic friction is proportional to the magnitude of the normal force, N o Fk = µkN - µk o coefficient of kinetic friction o always positive
