# Forces & Motion Laws

 normal force the "push" force from a surface onto a body in contact with that surface, perpendicular to the surface weight force force exerted by gravitational field in a mass, has downward direction, perpendicular to the surface of the earth weight equation w=mg gravitational force attractive force between two bodies having mass tension force a pulling force on a body usually via an attached cord, rope, cable, or such object kinetic friction resistive force that opposes the relative motion of 2 contacting surfaces that are moving past one another comparison of kinetic and static friction force required to cause a stationary object to begin moving is usually greater than the force necessary to keep it moving at constant speedkinetic friction < static friction relationship between object weight and kinetic friction kinetic friction will be greater when you try to move a heavy object relationship between applied force and static friction directly proportional; as applied force increases, static friction also increases, and same with decreasing Fs,max greatest applied force without the object moving, due to static friction static friction resistive force that opposes the relative motion of 2 contacting surfaces that are at rest, with respect to one anothermeasure of how rough or slippery something is; the force needed to get an object moving from a state of rest its magnitude depends on the amount of microscopic contact points between the surfaces relationship between friction forces and normal forces frictional forces are proportional to the magnitude of the normal forceif something is tilted, there is less normal force and less friction force Newton's third law if two objects interact, the force exerted before object 1 on object 2 is equal in magnitude and opposite in direction to the force exerted by object 2 on object 1 Newton's second law the acceleration of an object is directly proportional to the net force acting on it or inversely proportional to its mass Newton's first law an object at rest will remain at rest, and an object in motion at a constant velocity will remain in motion, unless otherwise acted upon by a net external force; law of inertia mass measure of how difficult it is to change an object's velocity inertia tendency of a mass to maintain its state of motion net external force acts on an object as a result of an interaction between an object and its accelerationsum of all external forces as velocity vectorsequivalent to the one force that would produce the same effect as all external forces combined static equilibrium an object is at rest translational equilibrium object moves at straight line with constant velocity inertial reference frame any place where Newton's laws can be applied (all except complex situations) action-reaction pairs force exerted when two systems interact, both systems "feel" the force in equal but opposite directionsnever act on the same object (normal and gravity are not a pair), but can interact without touching force the agent (or cause) of an acceleration, change in an object's velocity contact forces result from physical contact between objectspush, pull, friction, normal field forces no contact between objectsgravitational, electric, nuclear, weight, magnetic fundamental forces gravitational, electric, nuclear free body diagrams isolated only the forces affecting the motion of an object, assumed to be acting through a single point; leaves out forces within the object normal force equation with regards to angle btwn normal force and a vertical line Fn=mgcosΘ μk and μs coefficient of kinetic and static friction; ratio of forces of fricton to normal force acting between two objectslow with low friction and high with high friction relationship between mass and acceleration greater mass of an object, less it accelerates under an applied forcelighter objects accelerate much more than heavier objects equilibrium the state at which there is no change in a body's motionthere can be many forces acting on the object, they just all have to balance out net external force must be 0 SI force unit Newton, 1kgm/s2 field region of influence force diagram shows objects involved in a situation and the forces exerted on the objectall forces are drawn as if they act on a center point, no matter where the force is appliedforces exerted by the object are left out because they don't affect the object's motion AuthorGymnastxoxo17 ID267633 Card SetForces & Motion Laws Descriptiond Updated2014-05-25T15:33:41Z Show Answers