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Physics > 1) Motion, Forces and Conservation of Energy > Flashcards

1) Motion, Forces and Conservation of Energy Flashcards

1
Q

what is a scalar quantity? examples

A

size or magnitude but NO direction

-mass, speed, distance , energy

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2
Q

what is a vector quantity? examples?

A

size or magnitude and HAS direction

-force, weight, velocity, displacement, acceleration, momentum

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3
Q

what is velocity?

A

speed in stated direction

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4
Q

what is the equation for working out speed?

A

speed(M/s)= distance m / time s

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5
Q

what is the equation for average speed?

A

av. speed= total distance / total time

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6
Q

what does a straight line on a graph tell you about he speed?

A

constant spped

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7
Q

what does a curved line getting stepper tell you about the speed?

A

accelerating

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8
Q

what does a curved line getting flatter tell you about the speed?

A

decelerating

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9
Q

what does a flat line tell you about the speed?

A

stationary

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10
Q

what is the equation for acceleration?

A

acceleration m/s2 = change in velocity m/s
/ time taken
a=(v-u) / t

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11
Q

what is the equation for velocity?

A

v2 - u2 = 2 x a x X

X is the distance travelled

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12
Q

what can you interpret from a velocity/ time graph?

A
  • slope or gradient says acceleration

- area under graph gives distance

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13
Q

how do you work out the acceleration on a velocity time graph using the gradient?

A

acceleration = change in velocity/time taken

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14
Q

how can you use laboratory more accurate equipment to measure speed?

A

-light gates connected to data logger or computer

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15
Q

what is the typical speed for walling?

A

1.5m/s

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16
Q

what is the typical speed for running?

A

3m/s

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17
Q

what is the typical speed for cycling?

A

6m/s

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18
Q

what is the typical speed for sound in air?

A

330m/s

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19
Q

what is newtons first law?

A
  • resultant force on stationary object is zero it will stay stationary
  • if resultant force on moving object is zero it will stay at same speed and direction
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20
Q

what is newtons first law if the resultant force isn’t zero?

A

-acceleration/ deceleration

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21
Q

what is the formula which describes newtons second law?

A 
F= m X a
force(N)= mass (kg) X acceleration (m/s2)
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22
Q

what is the definition of weight? and what is it measured in?

A
  • force exerted due to mass and GFS

- measured in newtons

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23
Q

what is the equation for weight?

A

weight= mass X gravity

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24
Q

how is weight measured?

A

-newtonmeter

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25
Q

what is the relationship between weight and the gravity?

A

-weight is directly proportional to value of gravity

26
Q

how would you investigate force and acceleration?

A
  1. set up trolly with light gates and ramp
  2. record different velocity and time for different masses on the trolly
  3. work out acceleration by dividing velocity by time
  4. if changing mass slope must stay the same
27
Q

what conclusion is found after investigating force and acceleration?

A

-acceleration doesn’t depend on mass and stays similar throughout

28
Q

what happens to the speed and velocity of an object moving in a circular motion?

A
  • constant speed

- changing velocity

29
Q

why does circular motion happen? and what force must be acting? example.

A
  • must be a centripetal force
  • objects move at right angles to it
  • satellite around earth
30
Q

what is newtons third law?

A

for every action there is an equal and opposite reaction

31
Q

how does newtons third law act with equilibrium?

A

-eg if a man is pushing on a wall but the wall won’t move because the forces in the system are balanced.

32
Q

how does newtons third aw work with collisions?

A
  • total momentum before equals total momentum after
  • if 2 cars collide equal and opposite forces
  • both cars
33
Q

what is the definition of momentum?

A

product of mass and velocity

34
Q

what is the equation for momentum and what is it measured in?

A

p= m X v
kgm/s2
momentum= mass X velocity

35
Q

what is the definition of force?

A

rate of change of momentum.

36
Q

what is the equation for force using momentum?

A

mv - mu
F= ———-
t
force= change in momentum/ time

37
Q

what is a way of measuring human reaction times? and what is the formula used?

A
  • ruer drop test
  • hold ruler someone drops catch and measure distance
  • reaction time= (squ.root) 2 X distance/ gravity
38
Q

what is the average reaction time for a person to respond to a stimulus?

A

0.2-0.25 seconds

39
Q

what is stopping distance of a vehicle the sum of?

A

thinking distance + braking distance

40
Q

what are some of the factors which effect stopping distance?

A
  • tired
  • alcohol+drugs
  • mass of car
  • icy or wet conditions
41
Q

what are some of the factors which could effect a drivers reaction time?

A
  • tiredness
  • age
  • alcohol
  • distractions
42
Q

what is a danger of large decelerations?

A

typic forces of 10,000N exhorted on car

43
Q

what is the formula for change in gravitational potential energy?

A

GPE= m X g X change in vertical height

44
Q

what is the formula for kenetic energy?

A

kE= 0.5 X m X v2

45
Q

what is meant by conservation of energy?

A
  • can be stored, transferred or dissipated

- not created or destroyed

46
Q

how is energy changing when a ball is rolled up a slope?

A

-turns from kinetic energy to gravitational potential energy

47
Q

how is energy change when a bat hits a ball?

A
  • kinetic energy
  • thermal energy
  • sound energy
48
Q

how is energy changed when a rock is dropped from a cliff?

A
  • gravitational potential energy

- kinetic energy

49
Q

how is energy changed when a car is slowing dow?

A
  • kinetic energy

- thermal energy

50
Q

how is energy changed when a kettle has boiled water?

A
  • electrostatic energy

- thermal energy

51
Q

what is the definition of a closed system and what is an example?

A
  • energy can flow in and out
  • but no mass change
  • pan boiling water, with lid, no steam can escape
52
Q

how does energy have anything to do with closed systems?

A
  • energy transfers

- no change to total energy

53
Q

how are mechanical processes wasteful? and give example.

A
  • lead to risen temperature
  • energy stored in less useful ways
  • light + sound energy from TV absorbed into people rising their temperature
54
Q

how is energy dissipated? example.

A
  • some usefully transferred some dissipated

- TV giving out heat

55
Q

what are some of the ways of reducing unwanted energy transfers?

A

lubrication- reduces friction, therefore reduces thermal energy
insulation- reduces energy transfer by heating, air gaps in walls

56
Q

what are the effects of thermal conductivity?

A
  • how well material transfers energy
  • metal has a high thermal conductivity
  • house walls have a low to keep heat in
57
Q

what is the equation for efficiency?

A

efficiency= useful energy/ total energy

58
Q

how can efficiency be increased?

A

thermal insulation

lubrication

59
Q

what are the main renewable energy resources?

A 
solar cells
bio-fuels - animals and pants 
tidal power
wind turbines 
hydroelectricity
60
Q

what are the main non- renewable energy resources?

A

nuclear fuels

fossil fuels

61
Q

what are some of the pattern and trends with energy use?

A
  • bio mass remained constant
  • mostly used fossil fuels
  • huge rise in energy usage
  • huge rise in population
  • increase in nuclear power

Physics (11 decks)

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