PLTW Principles of Engineering

PLTW Principles of Engineering Actual Mechanical Advantage (AMA) - answerratio of the magnitude of the resistance and effort forces applied to a system Effort Force - answerAn external force applied to an object Efficiency - answerThe ratio of useful energy output to the total energy input, or the percentage of the work input that is converted to work output Friction - answerThe resistance that one surface or object encounters when moving over another Fulcrum - answerfixed point around which a lever rotates Ideal Mechanical Advantage (IMA) - answerRatio of distance traveled by the applied effort and resistance force within a system. Idler Gear - answerA gear positioned between the driver and the driven gear used to change rotational direction. Moment - answerThe turning effect of a force about a point equal to the magnitude of the force times the perpendicular distance from the point to the line of action from the force. Pitch - answerDistance between adjacent threads in a screw. 6 Types of Simple Machines - answer-Inclined plane -Lever -Pulley -Screw -Wedge -Wheel and Axle Inclined plane - answerA flat surface set at an angle or an incline with no moving parts that is able to lift objects by pushing or pulling the load. Lever - answerA rigid bar to exert a pressure or sustain a weight at one point of its length by the application of a force at a second and turning at a third on a fulcrum. Pulley - answerA type of lever that is a wheel with a groove in its rim, which is used to change the direction or multiply a force exerted by a rope or cable. Screw - answerAn inclined plane wrapped around a cylinder, forming the path and pitch. Wedge - answerA substance that tapers to a thin edge and is used for splitting, raising heavy bodies, or for tightening by being driven into something. Wheel and Axle - answerTwo different sized circular objects that are attached together and turn as one. Static Equilibrium - answerA condition where there are no net external forces acting upon a particle or rigid body and the body remains at rest or continues at a constant velocity. Torque - answerA force that produces or tends to produce rotation or torsion. Sprocket - answerA toothed wheel whose teeth engage the links of a chain. 1st class lever - answerfulcrum in the middle; see-saw, hammer, scissors 2nd class lever - answerfulcrum at the end, load in the middle; wheel barrow, car-jack 3rd class lever - answerfulcrum at the end, effort in the middle; tweezers, baseball bat Fixed pulleys - answerSecured to a single spot, usually overhead; water well IMA: 1 Moveable pulleys - answerone end of the rope is fixed and the wheel is free to move No change in direction of force IMA: 2 Compound pulleys - answerMoveable pulley + fixed pulley Can change direction of force IMA: 2+ Block and tackle pulleys - answerMultiple fixed and moveable pulleys IMA: number of pulleys Voltage - answerThe potential difference measured in volts. The amount of work to be done to move a charge from one point to another along an electric circuit. Variable: V Unit: volts (V)