topic 1 - motion Flashcards

1
Q

vector quantity

A

a physical quantity with magnitude and direction

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2
Q

scalar quantity

A

a physical quantity with only magnitude and NO direction

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3
Q

examples of vectors (6)

A
force
velocity
displacement
weight
acceleration
momentum
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4
Q

examples of scalars (6)

A
speed
distance
mass
energy
temperature
time
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5
Q

distance

A

scalar quantity

how far an object has mooved

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6
Q

displacement

A

vector quantity

measures the distance and direction in a straight line from an objects starting point to its finishing point

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7
Q

speed

A

scalar quantity

how fast you’re going

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8
Q

velocity

A

vector quantity

speed in a given direction

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9
Q

speed (formula)

A

speed = distance / time

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10
Q

typical speeds
walking
running
cycling

A

walking 1.4m/s
running 3m/s
cycling 5.5m/s

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11
Q

typical speeds
wind speed
speed of sound in air

A

wind speed 5-20m/s

speed of sound in air 340m/s

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12
Q

3 ways of measuring speed

A

light gates (good for short time intervals, and get rid of human error caused by reaction times)
rolling tape measure, markers and a stopwatch
use a video of the moving object

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13
Q

acceleration

A

the change in velocity in a certain amount of time

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14
Q

average acceleration formula

A

acceleration = (final velocity - initial velocity) / time

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15
Q

deceleration

A

negative acceleration

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16
Q

what is the acceleration due to gravity

A

10m/s^2

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17
Q

acceleration units

A

m/s^2

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18
Q

uniform acceleration

A

constant acceleration

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19
Q

constant acceleration formula

A

v^2 - u^2 = 2 x acceleration x distance

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20
Q

what does the gradient on a distance time graph show you

A

the gradient at any point gives the speed of the object

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21
Q

what does the flat on a distance time graph show you

A

that the object has stopped

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22
Q

what does the curve on a distance time graph show you

A

that the object is accelerating
the curve getting steeper means that it is speeding up
a levelling off curve means that it is slowing down

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23
Q

how to calculate speed from distance time graph

A

draw tangent to the line

change in y or change in distance / change in x or change in time

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24
Q

what does the gradient on a velocity time graph show you

A

shows you the acceleration

because change in velocity / time = acceleration

25
Q

what does the flat section on a velocity time graph show you

A

an object is travelling at a steady spped

26
Q

what does the curve on a velocity time graph show you

A

changing acceleration

27
Q

what does a straight DIAGONAL line on a velocity time graph show you

A

uphill section - acceleration

downhill section - deceleration

28
Q

how to calculate distance travelled from a velocity time graph

A

calculate the area of underneath the graph

29
Q

newton’s first law

A

if the resultant force on a stationary object is zero, the object will remain stationary
if the resultant force on a moving object is zero, it will carry on moving at a constant velocity (same direction)

30
Q

according to newton’s first law when does velocity change

A

when the resultant force is not zero

31
Q

how does newton’s first law explain circular motion(4)

A

if an object is travelling in a circular orbit, it is constantly changing direction so it is constantly changing velocity

this means that the object is constantly accelerating

according to newton’s first law there must be a resultant force therefore acting on the object

this force acts towards the centre of the circle and is known as a centripetal force

32
Q

what is newton’s second law

A

force and acceleration are directly proportional

acceleration thought is inversely proportional to the mass of an object

33
Q

formula for newton’s second law

A

force(N) = mass(kg) x acceleration(m/s^2)

34
Q

inertia

A

the tendency for an object to keep moving with the same velocity

35
Q

inertial mass

A

how difficult it is to change the velocity of an object

36
Q

inertial mass (formula)

A

mass = force/acceleration

37
Q

what is newton’s third law

A

when two objects interact, they exert equal and opposite forces on each other

38
Q

how to test newton’s second law (the trolley experiment) (7)

A

1) measure mass of trolley, unit masses and hanging hook ; measure length of the piece of card that will interrupt the light gate beams
2) adjust height of ramp so trolley just starts to move
3) mark line on ramp just before 1st light gate so trolley travels same distance every time
4) attach trolley to hanging mass by string ; hold trolley still at start line then let go so it starts to roll down
5) weight of hook and masses attached provide accelerating force (mass of hook x acceleration due to gravity)
6) each light gate will record the time when the trolley passes through and speed of the trolley at that time - use this to calculate the acceleration
7) repeat at least three times and calculate an average acceleration from the results

39
Q

how should you vary mass in the trolley experiment

A

add masses to the TROLLEY , not the HOOK, so that you change the mass of the system not the force acting on it

40
Q

how should you vary force in the trolley experiment

A

add masses to the hook FROM the trolley
this increases the accelerating force whilst the mass of the system stays the same (because you are shifting the location of the masses within the system)

41
Q

explain your expected results for the trolley experiment

A

when you increase mass
the whole mass increases, force applied stays the same so there is a decrease in acceleration

when you increase force
force increases but mass stays the same (force = mass x acceleration) so acceleration must increase

42
Q

mass

A

scalar value

the amount of stuff in an object

43
Q

weight

A

the force acting on an object due to gravity

44
Q

weight formula

A

weight = mass x gfs

45
Q

momentum formula

A

momentum = mass x velocity

46
Q

what is momentum measured in

A

kg m/s

47
Q

conservation of momentum

A

in a closed system, the total momentum before an event/collision is the same as the total momentum after the event

48
Q

when a resultant force acts on an object for a certain amount of time

A

it causes a change in momentum

49
Q

force from acceleration using momentum (formula)

A

force = (mass x v) - (mass x u) / time

50
Q

how to test reaction times with the ruler drop test

A

1) sit with arm resting on edge of table and have someone hold ruler so it hangs between thumb and forefinger, lined up with zero
2) with no warning the ruler should be dropped and you should try to catch it
3) measurement on the ruler is how far it dropped in the time taken to react (the longer the distance the longer the reaction time)
4) you can calculate reaction time roughly because acceleration due to gravity is constant
5) repeat lots and calculate mean reaction time

51
Q

stopping distance =

A

stopping distance = thinking distance + braking distance

52
Q

thinking distance

A

the distance the car travels in the driver’s reaction time

53
Q

braking distance

A

the distance taken to stop once the brakes have been applied

54
Q

two factors affecting thinking distance

A

speed - the faster you’re going the further you travel before reacting
reaction time

55
Q

4 factors affecting reaction time

A

tiredness
drugs
alcohol
distractions

56
Q

4 factors affecting braking distance

A

your speed
friction between tyres and the road
how good your brakes are
mass of the car

57
Q

crumple zones

A

areas at the front and back of a vehicle which crumple up easily in a collision, increasing the time taken to stop
this lowers the force from a fast deceleration making it less dangerous

58
Q

energy is car’s kinetic energy store = work done by brakes (formula0

A

1/2 x mass x velocity ^2 = force x distance

59
Q

estimiated mass of car

A

1000kg