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Physics > Work, Power, and Energy > Flashcards

Work, Power, and Energy Flashcards

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1
Q

factors affecting work done

A
  1. magnitude of force applied
  2. displacement produced by the force
    (3. angle between force and displacement)
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2
Q

amount of work done is equal to?

A

the product of the force applied on it and the displacement of the point of application of force, in the direction of force

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3
Q

work is scalar/vector

A

scalar

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4
Q

if a force displaces a body in direction other than direction of force, amount of work done can be determined by…

A
  1. finding the component of displacement along the force
  2. finding the component of force along the displacement
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5
Q

Special cases for work done

A
  1. if displacement is in the direction of force, work done is positive
  2. when displacement is normal to the direction of force, work done is 0.
  3. if displacement is in a direction opposite to force, work done is negative
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6
Q

work done by the force of gravity

A

work done by the force of gravity is the same whether the body comes down from a certain height using stairs or a slope or lift. if the body goes up, work done is negative

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7
Q

define 1 joule

A

1 joule of work is said to be done when a force of 1 newton displaces a body through a distance of 1 meter in its own direction

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8
Q

CGS unit of work

A

1 erg= 1 dyne * 1 cm

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9
Q

1 joule is how many erg

A

1 joule= 10^7 erg

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10
Q

define power

A

the rate of doing work (scalar)

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11
Q

power depends on

A
  1. amount of work done by the source
  2. time taken by the source to do said work
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12
Q

power is also equal to

A

force * average speed

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13
Q

SI and CGS unit of power

A

watt (W)
erg per second

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14
Q

define 1 watt

A

if 1 joule of work is done in 1 second, power spent is 1 watt

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15
Q

1 watt is how many erg per sec

A

1 W = 10^7 erg per second

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16
Q

1 HP is how many watts

A

1 HP= 746 W= 0.746 kW

17
Q

define energy

A

the capacity of a body to do work (scalar)

18
Q

when is there no transfer of energy

A

when a body is acted upon by a force normal to the direction of displacement

19
Q

units of energy

A

SI: joule
CGS: erg
bigger units: watt hour. kilowatt hour
for heat energy: calorie
Electron volt

20
Q

define 1 Wh

A

1 watt hour is the energy spent by a source of power 1 W in 1 hr

21
Q

define 1 calorie

A

1 calorie is the heat energy required to raise the temperature of 1 g of water by 1 degree C

22
Q

1 calorie is how many J

A

1 cal= 4.18 J
1 J= 0.24 cal

23
Q

what is electron volt

A

the energy transfer in case of atomic particles is very small, so it is measured in electron volt eV

24
Q

define 1 eV

A

1 eV is the energy gained by an electron when it is accelerated through a potential difference of 1 V

25
Q

how many joules is 1 eV

A

1 eV= 1.6 * 10^-19 J

26
Q

define potential energy

A

the energy possessed by a body at rest due to its position or size and shape is called potential energy

27
Q

kinds of potential energy

A
  1. gravitational potential energy (negative)
  2. elastic potential energy
28
Q

gravitational PE of a body at a point

A

work done by force of attraction of the earth in getting that body from infinity to that point.
OR
the amount of work done in lifting that body at a height against force of gravity

29
Q

define kinetic energy

A

the energy possessed by a body due to its state of motione

30
Q

expression of KE

A

the KE possessed by a moving body is equal to the amount of work which the moving body is capable of doing before coming to rest.

31
Q

KE and momentum are related as

A

KE= p^2/ 2m

32
Q

work-energy theorem

A

the increase in kinetic energy of a moving body is equal to the work done by a force acting in the direction of the moving body.

33
Q

three forms of KE

A
  1. translational (straight line)
  2. rotational (rotating about an axis)
  3. vibrational (to and fro from a mean position)
34
Q

forms of energy

A
  1. solar
  2. heat
  3. hydro
  4. light
  5. chemical
  6. electrical
  7. mechanical
  8. nuclear
  9. wind
35
Q

define light energy

A

it is a form of energy in the presence of which other objects are seen

36
Q

define electrical energy

A

when two dry bodies are rubbed together, they get charged due to the movement of free electrons from one body to the other body.

37
Q

define nuclear energy

A

the energy released due to loss in mass during the processes of nuclear fission and fusion, is called nuclear energy.

38
Q

define geothermal energy

A

the energy released in nuclear disintegrations in the interior of earth, gets stored deep inside and is called geothermal energy.

39
Q

principle of conservation of energy

A

energy can neither be created nor be destroyed. it only changes from one form to another.

Physics (12 decks)

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