My Quizlet - Kaylie
Terms in this set (44)
Occurs when a force acts on an object to move it in a direction parallel to the force vector. ( W )
A basic mechical device that either reduces effort or increases the magnotude of motion for a given input motion when doing a certain amount of work.
Load or resistance
The system on which work is done by a machine; the resistance force acting on a simple machine.
What is one of the best sources of good ideas for developing technologies such as simple machines?
One of the best sources of good ideas for developing technologies such as a simple machine is to look at God's work in nature to gives us a good starting point and to also look at nature and plants.
What is the definition of mechanical work? SI unit?
Occurs when a force acts on an object to move it in a direction parallel to the force vector. The SI unit is joules ( J ).
What is the definition of power? SI unit?
Rate of doing work. The SI unit is watt ( W ).
What is a simple machine? What are three categories of simple machines?
The three general categories of simple machines is levers, wheels and axles, and inclined planes. They are called simple machines because these are the parts that other machines are built on.
What does a simple machine NOT do?
A simple machine does not do less work, it less effect for the same amount of work.
What is the resistance of a system called?
What is resistance force?
The force exerted on a simple machine.
What is effort force?
The force exerted on a simple machine to do work on a load.
What is mechanical advantage?
A measure of the reduction in effort to do a certain amount of work when using a simple machine. ( MA )
Actual Mechanical Advantage (AMA) vs Ideal Mechanical Advantage (IMA)
Explain the distance principle.
The principle that the distance an effort force must be exerted when using a simple machine increases inversely in proportion to the reduction of effort according to the MA of the machine; a consequence of the law of the conservation of energy, which states that work input must be equal to work output.
What is a lever?
A simple machine that can be modeled as a rigid bar that pivots about a fulcrum to exert an effort moment against a resistance moment.
What is a fulcrum?
The point about which a lever pivots or rotates.
What is rotational equilibrium?
The condition in which the sum of all the torques on a system is zero- the system will rotate either at a constant speed or not begin to rotate at all; the equivalent to Newton's first law for linear motion.
What is a moment?
Quantity produced by a force exerted perpendicular to a lever at the end of a moment arm. Also called a torque.
What is the moment arm?
The distance between an applied force and the pivot point of a lever when computing a moment or torque. Also called a lever arm.
Give the formula the expressed the law of moments.
What is an effort arm?
The moment arm of the effort force in a lever system.
What is a resistance arm?
The moment arm of the load or resistance force in a lever system.
First class lever
The fulcrum is located between the effort and the resistance. Examples are crowbar, seesaw, and scissors.
Second class lever
The fulcrum is at the end of the lever arm and the resistance between the fulcrum and the effort. Examples are wheelbarrow and bottle opener.
Third class lever
The fulcrum is at the end of the lever arm and the effort is between the resistance and the fulcrum. Examples are baseball bat, tweezers, and fishing pole.
How do you find the mechanical advantage of a lever?
What is a wheel?
Is usually a disk that rotates around an axis, but functionally, it can be any rotating object in which a force, creating a mechanical moment.
What is an axle?
Is a smaller disk, cylinder, or shaft that attaches to the wheel at its rotational axis.
How do you find the mechanical advantage of the wheel and axle?
What is a gear?
Is a modified form of a wheel and axis. It consists of a wheel with notches or teeth around its circumference.
Resistance gear vs. the effort gear
How is the mechanical advantage of a set of gears determined?
The Ideal MA of a gear system equals the number of teeth in the resistance gear divided by the number of teeth in the effort gear.
What is a pulley?
A wheel and axle system with a groove around the perimeter of the wheel in which a rope or cable moves with the wheel as it rotates.
What is a block and tackle?
An arrangement of fixed and movable pulleys connected by ropes or cables that provides a mechanical advantage to do mechanical work. Also called pulley gang.
How is the mechanical advantage for pulleys determined?
What is an inclined plane?
a sloping ramp up which heavy loads can be raised by ropes or chains.
How is the IMA of an inclined plane determined?
IMA= incline length/height
What is a wedge?
A three-dimensional object that uses inclined planes to exert a force to spread a material apart as it's forced into the material.
Why is a double-sided wedge needed sometimes?
A double wedge is necessary because the tip needs more support close to the edge to strengthen it and keep it from dulling or breaking.
What is a screw?
A fastener that consists of a long, thin wedge wrapped around a shaft in a spiral called a screw thread. Screws exert large forces to hold objects together.
What is TPI?
The number of threads per inch
What is the pitch?
The distance between two adjacent threads on metric screws and bolts, measured in millimeters. A smaller pitch implies greater holding power.
How is the mechanical advantage determined for screws?
Give an application of a screw that does not involve fastening two things together.
Two application of a screw that does not involve two things together is an apple peeler and a jack screw.