# Force and Motion II

## Sample Problem Force And Motion

Sample Problem Force And Motion Shows a coin of mass m at rest on a book that has been tilted at an angle 0 with the horizontal. By experimenting, you find that when 0 is increased to 13°, the coin is on the verge of sliding down the book. SOLUTION: If the book were friction less, the coin …

## Sample Problem Force And Motion 11

Sample Problem Force And Motion 11 A woman pulls a loaded sled of mass along a horizontal surface at constant velocity. The coefficient of kinetic friction between the runners and the snow is 0.10, and the angle . SOLUTION: We need three Key Ideas here: 1. Because the sled’s velocity is constant, its acceleration is zero in spite …

## Sample Problem Force And Motion 11

Sample Problem Force And Motion 11 If a car’s wheels are locked (kept from rolling) during emergency braking, the car slides along the road. Ripped-off bits of tire and small melted sections of road form the skid marks that reveal that cold-welding occurred during the slide. SOLUTION: One Key Idea here is that, because the acceleration is assumed …

## Properties of Friction

Properties of Friction Experiment shows that when a dry and lubricated body presses against a surface in the same condition, and a force F attempts to slide the body along the surface, the resulting frictional force has three properties. Property 2. If the body begins to slide along the surface, the magnitude of the frictional force rapidly decreases …

## Friction

Friction Frictional forces are unavoidable in our daily lives. If we were not able to counteract them, they would stop every moving object and bring to a halt every rotating shaft. About 20% of the gasoline used in an automobile is needed to counteract friction in the engine and in the drive train. On the other hand, if …

## Force and Motion II

Force and Motion II Cats, who enjoy sleeping on window sills, are often kept in apartment  buildings. When a cat accidentally falls out of a window and onto a sidewalk, the extent of injury (such as the number of fractured bones or the certainty of death) decreases with height if the fall is more . than seven or eight floors. (There …