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- 1. Multiple Choice
Raising an auto in a service station requires work. Raising it twice as high requireshalf as much workthe same worktwice the workfour times the work - 2. Multiple ChoiceRaising an auto in a service station requires work. Raising it in half the time requireshalf the powerthe same power.twice the powerfour times the power
- 3. Multiple ChoiceThe energy due to the position of something or the energy due to motion is calledpotential energykinetic energymechanical energyconservation of energy
- 4. Multiple ChoiceAfter you place a book on a high shelf, we say the book has increasedelastic potential energy.chemical energykinetic energy.gravitational potential energy
- 5. Multiple ChoiceAn empty truck traveling at 10 km/h has kinetic energy. How much kinetic energy does it have when it is loaded so its mass is twice, and its speed is increased to twice?the same KEtwice the KEfour times the KEmore than four times the KE
- 6. Multiple ChoiceWhich of the following equations is most useful for solving a problem that asks for the distance a fast-moving crate slides across a factory floor in coming to a stop?F = maFt = ∆mvKE = 1/2mv2a. Fd = ∆1/2mv2
- 7. Multiple ChoiceA boulder at the top of a vertical cliff has a potential energy of 100 MJ relative to the ground below. It rolls off the cliff. When it is halfway to the ground its kinetic energy isthe same as its potential energy at that pointnegligibleabout 60 MJmore than 60 MJ
- 8. Multiple ChoiceIn an ideal pulley system, a woman lifts a 100-N crate by pulling a rope downward with a force of 25 N. For every 1-meter length of rope she pulls downward, the crate rises25 centimeters45 centimeters50 centimeters100 centimeters
- 9. Multiple ChoiceWhen 100 J are put into a device that puts out 40 J, the efficiency of the device is40%.50%.60%.140%.
- 10. Multiple ChoiceAn energy supply is needed for the operation of a(n)automobileliving cellmachineall of these
- 11. Multiple ChoiceThe main sources of energy on Earth aresolar and nucleargasoline and fuel cells.wind and tidalpotential energy and kinetic energy
- 12. Multiple ChoiceSuppose that you apply a 60-N horizontal force to a 32-kg package, which pushes it 4 meters across a mailroom floor. How much work do you do on the package?60 N × 4 m = 240 J60 x 32 = 19204 m x 32kg = 128 kg/m60N / 4m = 15 n/m
- 13. Multiple ChoiceWhen is work done on an object?Work is done when a net force acts on an objectthe object moves in the direction of the net force.when energy is being transferred from one place to another or transformed from one form to anotherWe observe the effects of energy when something is happening
- 14. Multiple ChoiceEquation to find Workforce x distance = workforce x acceleration = workpush x pull =workeffort x monster = my work
- 15. Multiple ChoicePower isthe rate (time interval) at which work is done.work x distanceforce x distanceF=ma
- 16. Multiple ChoiceIf a forklift is replaced with a new forklift that has twice the power, how much greater a load can it lift in the same amount of time? If it lifts the same load, how much faster can it operate?The forklift that delivers twice the power will lift twice the load in the same time, or the same load in half the time.it doesn't, it operates at the same speedup to four times faster
- 17. Multiple ChoiceHow can you calculate power?Power equals the amount of work done divided by the time interval during which the work is done.P = w x fpower equals the amount of work done multiplied by the time interval during which the work is doneP = m x a
- 18. Multiple ChoiceWhat are the two forms of mechanical energy?kinetic energy and potential energy.gravitational energy and thermal energychemical energy and biological energygas and the force
- 19. Multiple ChoiceMechanical energy isthe energy due to the position of something or the movement of something.The property of an object or system that enables it to do workthe rate at which work is done.Some work is done to change the speed of an object.
- 20. Multiple ChoiceName three examples of potential energy.elastic potential energy, chemical energy, and gravitational potential energy.mechanical, fossil fuels, and thermal energythe force, the pacific ocean, and the hulk
- 21. Multiple ChoiceThe potential energy due to elevated positions isthermal potential energygravitational potential energymechanical energyelastic potential energy
- 22. Multiple ChoiceHow are work and the kinetic energy of a moving object related?The kinetic energy of a moving object is equal to the work required to bring it to its speed from rest, or the work the object can do while being brought to rest.Energy that is stored and held in readinessIt can be transformed from one form into another, but the total amount of energy never changestransfers energy from one place to another or transforms it from one form to another.
- 23. Multiple ChoiceWhat does the law of conservation of energy state?energy cannot be created or destroyed. It can be transformed from one form into another, but the total amount of energy never changes.a moving object is equal to the work required to bring it to its speed from rest, or the work the object can do while being brought to rest.the energy due to the position of something or the movement of something.the rate (time interval) at which work is done
- 24. Multiple ChoiceHow does a machine use energy?transfers energy from one place to another or transforms it from one form to anotheris the ratio of useful energy output to total energy inputsome energy is transformed into atomic or molecular kinetic energya moving object is equal to the work required to bring it to its speed from rest, or the work the object can do while being brought to rest.
- 25. Multiple ChoiceWhat is the work-energy theorem?states that whenever work is done, energy changes.states that energy is created, work is donesays that work and energy are the samerequires work to be created in order for energy to be changed.
- 26. Multiple ChoiceWhat is the source of practically all of our energy on Earth?carbon dioxide.our bodiesthe sunthe force
- 27. Multiple ChoiceWhy can’t a machine be 100% efficient?Because wasted energy is dissipated as heat.a small fraction of input energy is converted into thermal energy.efficiency is about making heatdue to inventors not being smarter
- 28. Multiple Choiceis the ratio of useful energy output to total energy input—the percentage of the work input that is converted to work output.EfficiencyWorkPowerMachines
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