# Shared Flashcard Set

## Details

Physics and Human Affairs Test #3
N/A
26
Physics
04/15/2014

Term
 To what two quantities is work proportional?
Definition
 force and distance
Term
 Under what condition can a force act on an object and yet do no work on that object?
Definition
 if the object does not move
Term
 Suppose you slowly, and at constant speed, lift a book weighing 12 N from the floor to a shelf 2 m above the floor. Neglect air resistance. While lifting, the net force on the book is....
Definition
 zero
Term
 Suppose you slowly, and at constant speed, lift a book weighing 12 N from the floor to a shelf 2 m above the floor. Neglect air resistance. The work done by you on the book is....
Definition
 24 joules
Term
 Energy could be defined as...
Definition
 The ability (or capacity) to do work work that is stored for later use a property of each system (isolated collection of objects) that is transferred between systems by work of one system on another
Term
 One situation in which the law of conservation of energy is violated is....
Definition
 nonsense-no violations of this law have ever been observed
Term
 A wrecking ball has a mass of 500kg and the highest point of the ball is 5 m above the lowest point. The ball starts from rest at the highest point. Assume that no energy is lost to air resistance and use g= 10 m/s2 for the acceleration due to gravity. What is the maximum speed of the ball?
Definition
 10 m/s
Term
 A block of ice slides freely (without drag) down a slippery slope. The block starts from rest at the top of the slope, where it has a vertical height of 4 m above the bottom of the slope and where it has a gravitational energy of 1000 joules. At a quarter of the way down the slope (at 3/4 of the height from the bottom), the block's gravitational energy is...
Definition
 750 joules
Term
 You slowly lift a book from the floor and put it on the table. You then lift an identical book quickly from the floor and put it on the table. Each book starts from rest and ends at rest. Which of the following is true?
Definition
 The power used in the second case is greater
Term
 Which of the following statements are consistent with the Second Law of Thermodynamics?
Definition
 all of the above
Term
 The efficiency of a device is...
Definition
 its useful energy output divided by the total energy put into the device
Term
 A particular lightbulb produces 8 J of thermal energy while producing 2 J of radiant energy, and this is its entire energy output during this time. How efficient is the bulb?
Definition
 20%
Term
 The efficiency of a heat engine is defined to be...
Definition
 work output divided by thermal energy input
Term
 In one cycle of operation, the thermal energy input to a particular heat engine is 200 joules and the exhaust is 80 joules. The efficiency of the engine is...
Definition
 60 percent
Term
 A 75 watt lightbulb....
Definition
 consumes 75 joules of electric energy during every second
Term
 Suppose tha 100 W lightbulb has an energy efficiency of 5% and is turned on for one minute (60 seconds). During this time, the visible radiant energy output of the lightbulb is....
Definition
 300 J
Term
 Suppose you viewed a movie tha was running backwards. You woul see lots of odd things happening, streams would flow uphill, and so forth. If the odd "backward moving" things actually happened in nature, which principle of physics would be violated?
Definition
 The second law of thermodynamics
Term
 Which of the following statements is consistent with the Second law of Thermodynamics?
Definition
 All of the above
Term
 When the inside of a refrigerator is cooled, does thermal energy flow from hot to cold, or is it from cold to hot? Does this happen spontaneously, or is outside assistance required?
Definition
 From cold to hot. Since this is against the normal flow of thermal energy , outside assistance is required.
Term
 This is the triboelectric series: human hair, glass, rabbit fur, cat fur, amber, balloon, polyester, plastic wrap, hard rubber. A typical plastic hairbrush be made of hard rubber. Which of these is the best explanation of the "electric hair" that can occur when some people brush their hair?
Definition
 Electrons are brushed from the hair onto the brush, causing the brush and hair to be changed, so thats the hairs then repel each other while the brush attracts the hairs.
Term
 Current is measured in amperes (A or amp). Voltage is measured in volts (V). For an electrical circuit, which of the following are correct definitions?
Definition
 Current: amount of electric charge that passes any point in a circuit, each second. Voltage, the amount of ElectE that a battery gives to one coulomb of electrical charge.
Term
 If a lightbulb has a resistance of 40 ohms and a current of 2 amps, at what voltage is it operating?
Definition
 80 V
Term
 Object A has an electric charge that is 10 times larger than the charge on object B. When plced near each other, how does the force by A on B compare with the force by B on A?
Definition
 They are equal
Term
 Suppose that the electric force between two objects is 2 N and that you then halve the distance between the objects. The new force is...
Definition
 8 N
Term
 One difference between moving charges and stationary charges is that...
Definition
 moving charges exert both electric and magnetic forces, while stationary charges exert only electric forces
Term
 A changing magnetic field creates an electric field. This is one way of stating....
Definition