physics lesson 4 unit 4

machine

a device that transmits or modifies the force or the motion necessary to accomplish work

law of moments

a law that states that a force times a distance on one side of a fulcrum is equal to a force times a distance on the other side of a fulcrum -f1 x d1 = f2 x d2

lever

a machine that enables a person to redirect or dilute the force necessary to accomplish work by spreading it over a longer distance f1 x d1 = f2 x d2

Mechanical Advantage

a measurement of the amplification of a force gained through a machine -trade distance for force -M.A. effort arm/resistance arm

A type 3 lever

increases the distance the load moves which requires more effort. -fulcrum is used, it will be positioned on the top of the load arm.

wheel and axle

simple machine in which you gain Mechanical Advantage due to the attachment of a larger wheel to a smaller wheel. -M.A. = radius of wheel/radius of axle.

pulley system

simple machine that affords Mechanical Advantage through a system of ropes and pulleys. -M.A. determined by the number of strands of rope actually supporting the load.

fulcrum

the axis on which a bar can pivot; also called the point of rotation

type 1 lever

-fulcrum is between the effort arm and the resistance arm, -direction of the effort force versus the resistance is reversed, -M.A. is determined by the proximity of the fulcrum to the load (resistance). -sacrificing distance for effort

second type of lever

M.A. is gained by the difference between the distance from the resistance to the fulcrum and the distance from the effort to the fulcrum -easily around an axis. -effort and resistance forces travel the same direction. -resistance is placed between the fulcrum and the effort. -sacrificing distance for effort