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accelerate
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To gain velocity or increase speed in a given direction.
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acceleration
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The rate of change of velocity.
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angle
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A figure formed by the intersection of two lines. Angles are also used to measure distances around a circle.
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angular motion
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Circular motion that is measured in changes in angular position. Angular motion is measured in units of degrees or radians.
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applied force
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The energy or effort provided to a machine to perform work. Applied force has many forms, from the power of an electric motor to the push from human hands.
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area
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The amount of two-dimensional space. Area is also used to measure the outermost surface of an object.
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axis
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An imaginary straight line that passes through the center of an object. Objects typically rotate around an axis.
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belt and pulley system
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A setup on a machine consisting of two round, fixed pulleys. One pulley is powered and moves a belt, which in turn moves the other pulley.
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brake
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A device used to stop motion, usually through friction.
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cam
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A low-friction, circular lever consisting of a lobe and a shaft that transforms circular motion into linear motion. Cams are often used in combustion engines.
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centimeter
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A small unit of linear measurement in the metric system. One centimeter equals approximately 0.3937 inch in the English system.
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contact force
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A force that can cause or change motion of an object by touching it. Motors, gears, levers, and fluid power all operate through contact forces.
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decelerate
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To lose velocity or reduce speed in a given direction.
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degree
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A unit of angular measurement. There are 360 degrees in a complete circle.
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density
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The amount of mass within a specific volume. Objects with greater density increase in mass and weight.
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direction
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The path that an object takes when it moves.
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distance
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The linear space between two objects or points.
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dynamics
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The branch of the science of mechanics that deals with objects that are not in equilibrium.
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electromagnetism
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Magnetism produced by an electric current.
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energy
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The capacity to do work. Energy may be potential or kinetic and may appear as electrical, mechanical, thermal, or chemical energy.
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English system
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A standard system of measurements based on the inch, second, pound, and Fahrenheit degrees. English measurements are primarily used in the United States and England.
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equilibrium
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A state of sameness. Objects that are in equilibrium are either completely still or moving at a consistent rate.
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foot
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A unit of linear measurement in the English system. One foot equals twelve inches.
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force
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An influence that produces a change in an object's motion or state of rest. A force has a specific direction and magnitude.
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friction
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A force that resists motion between two objects that are in contact with each other. Smoother surfaces exhibit less friction, while rougher surfaces exhibit more friction.
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gear
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A disc or wheel that contains evenly spaced teeth around its perimeter. Gears are usually used in pairs to transmit energy and motion.
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gravity
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The force of attraction between masses. Gravity is the force that makes objects fall to the ground.
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hydraulic system
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A system that uses liquids to transmit motion to mechanical parts.
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inch
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A small unit of linear measurement in the English system. One inch equals approximately 2.54 centimeters in the metric system.
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inclined plane
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A simple machine consisting of a flat, angled surface used to raise objects. The mechanical advantage of an inclined plane increases with its length.
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inertia
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The tendency of an object to remain at rest until acted on by a force.
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kilometer
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A unit of linear measurement in the metric system. One kilometer equals 1,000 meters.
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kinetic energy
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Energy of an object that has been put in motion.
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linear motion
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Motion that takes place along a straight line. Linear motion can be measured using the English or metric system.
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load
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The opposition to applied force, such as a weight to be carried or moved.
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magnet
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A device or object that attracts iron and produces a magnetic field.
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magnitude
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The measurement of the amount of an applied force.
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mass
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The amount of matter in an object. Mass gives an object weight when it is acted upon by gravity.
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matter
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The material or substance that makes up an object. Matter has both mass and volume.
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mechanics
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The branch of physics concerned with the motion of objects. Mechanics deals with different forces that cause or prevent motion.
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meter
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A base unit of linear measurement in the metric system. One meter equals 10 centimeters.
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metric system
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A standard system of measurements based on the meter, second, kilogram, and Celsius degrees. The metric system is internationally recognized.
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mile
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A unit of linear measurement in the English system, used for long distances. A mile contains 5,280 feet.
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momentum
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The quantity of motion affecting an object. Momentum is mass multiplied by the velocity of an object.
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Newton's Laws of Motion
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A set of three rules that describe the behavior of moving objects.
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non-contact force
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A force that can cause or change motion of an object without actually touching it. Gravity and magnetic forces are non-contact forces.
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perpendicular
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Forming a right angle by intersecting another line.
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pneumatic system
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A system that uses air or gases to transmit motion to mechanical parts.
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point of application
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The place on the object where the force is applied. Point of application can affect forces such as torque and momentum.
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potential energy
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Stored energy with the potential to do work. Potential energy is often the result of an elevated position that can be acted upon by gravity.
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pulley
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A circular device that is used to raise or lower a load or transmit motion. A pulley may be moveable or fixed.
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radian
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A unit of angular measurement for the metric system. One radian is equal to approximately 57.3 degrees.
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revolutions per minute
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The number of times a component rotates 360 degrees, or in a complete circle, in one minute. Revolutions per minute (rpm) is a measurement of rotary speed.
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right-hand rule
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A method of determining the direction of rotary movement by wrapping one's right-hand fingers around the axis of rotation. Clockwise rotation points the thumb toward the person, and counterclockwise rotation points the thumb away.
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rotary motion
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Spinning or turning motion that takes place around an axis, without a change in linear position.
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rotary speed
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A measure of circular motion found by counting the number of revolutions that occur in a specific amount of time.
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rotary velocity
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The angular change of position in a specific amount of time. Rotary velocity is measured in either degrees per second or radians per second.
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scalar quantity
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An amount or measurement that is not related to direction. Speed, volume, and temperature are scalar quantities.
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see saw
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A long, narrow board balanced in the middle on a fulcrum in such a way that as one end goes up, the other goes down.
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speed
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The amount of distance traveled in a given period of time. Speed is used to measure both linear and rotational movement.
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static electricity
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A buildup of electric charge on an object or a person. When discharged, static electricity can cause a slight shock.
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statics
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The branch of the science of mechanics that deals with objects that are in equilibrium. A static object is either completely still or moving at a consistent rate.
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temperature
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The amount of hotness or coldness of an object.
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torque
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A force causing rotation.
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vector quantity
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An amount or measurement that is related to a direction. Velocity, acceleration, and weight are vector quantities.
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velocity
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The combination of an object's speed and direction of motion. Unlike speed, velocity always implies a direction.
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volume
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The amount of three-dimensional space occupied by an object.
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weight
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The force of a mass due to gravity. Without gravity, objects have no weight.
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wheel and axle
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A simple machine consisting of a round disc or wheel with a central pole at its axis.
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work
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The result of a force applied to an object and the distance through which the force is applied. In an equation, work is force multiplied by distance.
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