Henry County School District



Ch. 14: Work, Power & Machines Define:WorkJoulePowerWattHorsepowerMachineInput forceInput distanceWork inputOutput forceOutput distanceWork outputMechanical advantageActual mechanical advantageIdeal mechanical advantageEfficiency1.A force acting on an object does no work if the force is not ___________________________ the object’s motion2.The joule is the unit of measure for ______________3.If you exert a force of 10.0 N to lift a box a distance of 0.9 m, how much work do you do?4.The watt is the SI unit of ______________________________5.The power of a machine measures ________________________________________________________6.If you exert a force of 700 N to walk 6 m up a flight of stairs in 6 s, how much power do you use?7.To increase power, you can __________ the amount of work you do in a given amount of time, or you can do a given amount of work in __________ time.8.A 1500-W motor might also be rated as a _______________ horsepower motor.9.A machine is a device that can multiply _____________10.How can a machine make work easier for you?11.The actual mechanical advantage of a machine is ________ than the ideal mechanical advantage of the machine.12.If you know the input distance and output distance of a machine, what can you calculate?13.If you have to apply 40 N of force on a crowbar to lift a rock that weights 400 N, what is the actual mechanical advantage of the crowbar?14.A 120-m long ski lift carries skiers from a station at the foot of a slope to a second station 40 m above. What is the IMA of the lift?15.Reducing friction in a machine __________ its efficiency.16.The efficiency of a machine is always less than 100 percent because ________________________________17.A mechanical device requires 420 J of work to do 230 J of work in lifting a crate. What is the efficiency of the device?18.An inclined plane reduces the effort force by ___________ the distance through which the force is applied19.An ax is an example of which type of simple machine?20.The ideal mechanical advantage of a pulley system is equal to the ______________________________________.21.A machine is classified as a compound machine if it is made up of _______ or more simple machines that operate together.22.A girl lifts a 160-N load a height of 1 m in a time of 0.5 s. What power does the girl produce? Show your work.23.A force of 11 N is applied to the handle of a screwdriver being used to pry off the lid of a paint can. As the input force moves through a distance 0.3 m, the screwdriver does 3 J of work on the lid. What is the efficiency of the screwdriver? Show your work.Figure 14-224. What is the IMA of the ramp in Figure 14-2? Show your work.25. If the ramp shown in Figure 14-2 was coated with a smoother surface, how would the AMA of the ramp change?Ch. 15: EnergyDefine:EnergyKinetic energyPotential energyGravitational potential energyElastic potential energyMechanical energyThermal energyChemical energyElectrical energyElectromagnetic energyNuclear energyEnergy conversion1.Work is a transfer of _________________2.The energy of motion is called ______________________________3.A small 20-kilogram canoe is floating downriver at a speed of 2 m/s. What is the canoe’s kinetic energy?4.List several examples of an object with elastic potential energy?5.Why is the gravitational potential energy of an object 1 meter above the moon’s surface less than its potential energy 1 meter above Earth’s surface?6.A 4-kilogram cat is resting on top of a bookshelf that is 3 meters high. What is the cat’s gravitational potential energy relative to the floor if the acceleration due to gravity is 9.8 m/s2?7.What does the law of conservation of energy explain?8.The mechanical energy of an object equals its _________________________________ + ___________________________________9.What does equation E = mc2 explain?10.A 0.47-kg squirrel jumps from a tree branch that is 3.5 m high to the top of a bird feeder that is 1.2 m high. What is the change in gravitational potential energy of the squirrel? (The acceleration due to gravity is 9.8 m/s2.) Show your work.Roller Coaster Video1.When a roller coaster moves down a hill, __________ energy is converted into __________ energy2.Which type of energy do you always have at the top of the first hill on a roller coaster?3.As you go over a hill, inertia causes you to move up out of your seat and you experience a _____ G force.4..An object in motion __________________________ unless acted on by an unbalanced force.5.Roller coasters obey the law of motion that states that for every action, there is an ____ and opposite reaction ................
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