Energy, Work, and Simple Machines Flashcards

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1
Q

Efficiency

A

Can be calculated by comparing a machine’s output work to its input work

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2
Q

Machine

A

A device that changes the magnitude or the direction of a force

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3
Q

Compound machine

A

Consists of 2 or more simple machines linked so that the resistance force of one machine becomes the effort force of the second machine

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4
Q

Resistance force

A

the force exerted by a machine

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5
Q

watt

A

a unit of power defined as 1 joule per second

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6
Q

effort force

A

the force exerted by a person on a machine

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7
Q

work-energy theorem

A

states that the work done on an object equals the change in kinetic energy of the object

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8
Q

energy

A

the ability of an object to produce a change in itself or its surroundings

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9
Q

kinetic energy

A

the energy that results from the motion of an object

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10
Q

power

A

the rate of doing work

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11
Q

mechanical advantage

A

the ratio of the resistance force of a machine to its effort force

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12
Q

why is gasoline called a ‘miracle’ in the film

A

Gas is relatively cheap, it leaves no ash or residue, has a high yield

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13
Q

joule

A

the SI unit used for work

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14
Q

ideal mechanical advantage

A

calculated by comparing the effort distance to the resistance distance

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15
Q

work

A

when an applied force is multiplied by the distance through which the force is applied

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16
Q

What makes electric cars still expensive

A

Batteries are expensive

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17
Q

What does the area under the force-displacement graph represent?

A

the work done on the object

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18
Q

what are 2 major advantages of natural gas as an energy source compared to the other fossil fuels

A

Natural gas is less expensive
environmental friendly; burns cleaner

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19
Q

What is the equation for finding work?

A

w = fd

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20
Q

Work and energy are measured in?

A

Joules

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21
Q

do you think nuclear power is a safe form of energy

A

it is very safe because they can withstand drastic weather and the plants are very secure

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22
Q

Explain the relationship between work and energy

A

Energy is the ability to do work. When you do work to move an object, you’re changing the object’s energy

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23
Q

What is the equation for finding power?

A

W/T or FD/T

24
Q

Power is measured in?

A

Watts

25
Q

Power can be described as..

A

the rate of energy transfer

26
Q

In what unit is work measured?

A

Joules

27
Q

what does the film say that you and I should do with the global energy demand

A

suggest nuclear, natural gas, and renewable energy be combined to see 50 year crossover.

28
Q

Which of the following is NOT a way to increase power

A

increase time

29
Q

why is the documentary called switch

A

because they are looking for ways to switch their prime,old fashioned energy sources to more environmental friendly and future ones

30
Q

Which of the following would produce the greatest increase in the kinetic energy of a moving object?

A

doubling its velocity

31
Q

what is not a part of the human body lever system

A

nerve fibers

32
Q

A baseball and a ping pong ball are both shot from a slingshot with equal velocity. Which object has the greater velocity?

A

The baseball, it has a greater mass

33
Q

A diver doing a somersault has a greater angular velocity in the

A

tuck position, is at more of an angle (i think..)

34
Q

when you use a hammer to strike a nail, what class lever is this

A

first

35
Q

How does the kinetic energy of a car traveling at 16 m/s compare with the kinetic energy of the same car traveling at 8 m/s?

A

it is 4 times greater (the velocity gets squared)

36
Q

when you use a hammer t remove a nail using the claw, what class lever is this

A

third

37
Q

machine

A

a device that changes the magnitude or direction of a force

38
Q

energy

A

the ability of an object to produce a change in itself or its surroundings

39
Q

How much work would have to be done on a truck with a kinetic energy of 2x10^4 J to reduce its kinetic energy by half

A

1 x 10^4

40
Q

kinetic energy

A

energy that results from motion of an object

41
Q

potential energy

A

energy of storage due to its position relative to other objects

42
Q

A car has a kinetic energy of x J 7.5 s later it moves in the opposite direction with the same speed. What kinetic energy does it have?

A

xJ

43
Q

power

A

the rate of doing work

44
Q

hydrothermal and geothermal

A

this type of energy is created by hot spots; areas where earth’s core heat comes to surface

45
Q

A car has a kinetic energy of x J 7.5 s later it moves in the opposite direction with 3 times its initial speed. What kinetic energy does it have?

A

9x, velocity is squared

46
Q

A 6kg ball is travelling at 5m/s, what is its kinetic energy?

A

75 J

47
Q

hydroelectric

A

if an area has flowing water and has the money to build a damn to connect it to the electricity grid, then they can use this form of renewable energy

48
Q

If the velocity of the ball in question 16 doubles, its kinetic energy will be..

A

300 J

49
Q

Biomass

A

This source can be made from scraps of plant, grain, wood, and other types of biological material; it converts a solid to a liquid form to use instead of gas in vehicles

50
Q

nuclear energy

A

this type of energy relies o stellar energy; splitting of heavy atoms and the combining of lighter ones

51
Q

Waves

A

This type of energy is produced when electricity generators are placed on the surface of the ocean. The energy provided is most often used in desalination plants, power plants, and water pumps.

52
Q

wind turbines/ generators

A

this type of energy is used throughout areas of the midwest and in the southern regions of the U.S and can be a way to generate power to large areas in a fairly inexpensive way

53
Q

Conventional Batteries

A

This source of energy is largely used for powering low voltage devices that are not used often. Its life and endurance is dependent on the apparatus it will energize and the chemical agent involved in its makeup

54
Q

hydrogen fuel cells

A

this source is often compared to batteries; both convert the energy produced by a chemical reaction into usable electric power

55
Q

Indirect Natural Gas

A

Converting landfill gasses into a source of renewable energy is beneficial because it reduces greenhouse-gas emissions and can generate revenue from the sale of the electricity

56
Q

solar cells

A

this device absorbs light energy from the sun and converts it into usable forms of energy

57
Q

Standard Electrical Power

A

This type of energy is significant because our society uses large amounts of it and it depends on the use of power plants that convert some other kind of energy into it.