# Physical Science Vocab

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Distance how far an object moves Displacement distance and direction of an objects change in postion from the starting point Velocity the speed and direction of a moving object Instantaneous speed speed of an object at a given point in time; is constant for an object moving with constant speed and changes with the time for an object that is slowing down or speeding up Constant speed speed that stays the same Force a push or pull exerted on an object Inertia resistance of an object to a change in its motion Balanced force forces on an object that combine to give a zero net force and don't change the motion of the object Unbalanced force an unequal force on an object Net force sum of the forces that are acting on an object Acceleration rate of change of velocity; can be calculated by dividing the change in the velocity by the time it takes the change to occur Momentum property of a moving object that equals its mass times its velocity Sliding friction frictional force that opposes the motion of two surfaces sliding past each other Rolling friction when one object is rolling across another Static friction when neither object is moving Friction force that opposes the sliding motion between two touching surfaces Air resistance force that opposes the motion of objects that move through the air Centripetal force a net force that is directed toward the center of a curved or circular path Gravitational force the force of attraction between all masses in the universe Projectile any object that is propelled through space by the exertion of force Energy the capacity for work or vigorous activity Kinetic energy energy a moving object has because of its motion depends on the mass and speed of the object Gravitational potential energy energy stored by objects due to their position above Earth's surface; depends on the distance above Earth's surface and the object's mass Chemical potentian energy energy stored in chemical bonds Elastic potential energy energy stored when an object is compressed or stretched Mechanical advantage ratio of the output force exerted by a machine to the input force applied to the machine Work transfer of energy that occurs when a force makes an object move; measured in joules Power amount of work done or the amount of energy transferred divided by the time required to do the work or transfer the energy, measured in watts Machine device that makes doing work easier by increasing the force applied to an object, changing the direction of an applied force, or increasing the distance over which a force can be applied Simple machine machine that does work with only one movement ex. lever, pulley, wheel and axle, inclined plaine, screw and wedge Compound machine machine that is a combination of two or more simple machines Ideal machine the input work equals the output work Output force force applied by the machine Efficiancy of a machine a measure of how much of the work put into a machine is changed into useful output work by the machine Pulley a grooved wheel with a rope, chain, or cable running along the groove Wheel and axle a simple machine consisting of a shaft or axle rotate together Inclined plane a sloping surface such as a ramp that reduces the amount of force required to do work Screw an inclined plane wrapped in a spiral around a cylindrical post Wedge an inclined plane with one or two sloping sides Gear a wheel and axle with the wheel having teeth around its rim Electricity electric current used or regarded as a source of power Static electricity the accumulation of excess electric charge on an object Electrical conductor anything that carries or moves current Electrical insulator material that blocks the flow of electtric current across it Lightning flash of light in the sky caused by an electrical discharge Electroscope device for detecting the presence and determining the sign of electric charges by means of electrostatic attraction and repulsion, often between two pieces of gold leaf enclosed in a glass-walled chamber Electric current the net movement of electric charges in a single direction; measured in amperes Battery provides the voltage difference that is needed to keep current flowing in a circuit Dry cell battery a voltage-generating cell having an electrolyte in the form of moist paste Wet cell battery contains two connected plates made of different metals or metallic compounds in a conducting solution Charged by contact the process of transferring charge by touching or rubbing Charged by induction the rearrangement of electrons on a neutral object caused by a nearby charged object Electrical resistance the tendency for a material to oppose the flow of electrons changing electrical energy into thermal energy and light Series circuit the circuit has only one loop to flow through Parallel circuit contains two or more branches for current to move through Open circuit no curent flows through this circuit Closed circuit endless path for the flow of current Electrical fuse contains a small metal piece that melts if the current becomes too high Circuit breaker contains a pice of metal that bends when the current in it is so large that it gets hot Ohm's law the current in a circuit equals the voltage difference divided by the resistance; I=V/R Electrical power the rate at which electrical energy is converted to another form of energy Electrical energy energy made available by the flow of electric charge through a conductor; measured in kilowatt hours Output force the force applied by the machine Lever a bar that is free to pivot or turn around a fixed point Newton's 3rd law When one object exerts a force on a second object the second one exerts a force on the first that is equal in strength and opposite in direction Newton's 2nd law the acceleration of an object is in the same direction as the net force on the object Newton's 1st law an object at rest will remain at rest unless acted on by an unbalanced force Law of conservation of energy states that energy can never be created or destroyed Law of conservation of charge states that charge can be transferred from one object to another but can't be created or destroyed Law of conservation of momentum states that momentum can be transferred from one object to another AuthorAnonymous ID124684 Card SetPhysical Science Vocab DescriptionPhysical Science Vocab Updated2011-12-21T01:40:43Z Show Answers