momentum Flashcards

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1
Q

what is the principle of the conservation of momentum?

A

total momentum before = total momentum after in a closed system where no external forces act

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2
Q

what is newtons 1st law?

A

an object will remain at rest or continue moving with constant velocity unless acted on by a resultant force

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3
Q

what does a closed system mean?

A

no external forces

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4
Q

what is the formula for change in momentum?

A

change in momentum = force x time

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5
Q

what is the formula for force?

A

force = change in momentum/ time

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6
Q

what is newtons 3rd law?

A

object a pushes on object b and object b pushes on object a with an equal opposite force

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7
Q

what 3 things must happen in order for newtons 3rd law to take place?

A

must be the same type of force, act on different objects and act in different directions

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8
Q

what is the formula for change in momentum? (momentum)

A

final- initial

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9
Q

what are the 4 key points for safety?

A

1) write equation
2) increase time taken to stop
3) to change the same momentum the force needs to be smaller as time is greater
4) prevents injury

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10
Q

what is momentum measured in?

A

kgm/s

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11
Q

is momentum a scalar or a vector?

A

vector because it has magnitude & direction

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12
Q

what does the + or - sign show with a momentum value?

A

the direction

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13
Q

what does the value of the momentum show?

A

the magnitude

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14
Q

what does a + sign show for the momentum?

A

the direction is up or right

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15
Q

what does a - sign show for the momentum?

A

the direction is down or left

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16
Q

what equipment is needed for the investigation of momentum?

A
  • linear tracks with 2 carts
  • light gates, interface & computer
  • electronic balance
  • pasco file 1.05
17
Q

what do forces cause objects to do?

A
  • change shape
  • change speed
  • change direction
18
Q

what is the formula for resultant force?

A

resultant force = mass x acceleration

19
Q

why does Newton’s third law apply to the conservation of momentum?

A

it is Newton’s third law pairs that cause the momentum to change

20
Q

what is change in momentum also called?

A

impulse

21
Q

to change momentum over a longer time…

A

a smaller force is needed

22
Q

to change momentum over a shorter time…

A

a larger force is needed

23
Q

how do crumple zones prevent injury?

A
  • force = change in momentum/ time
  • crumple zones increase the time taken to stop
  • to change the same momentum, the force needs to be smaller as time is greater
  • prevents injury
24
Q

the conservation of momentum always applies when…

A

no external forces act

25
Q

what does the conservation of KE always depend on?

A

depends on the collision

26
Q

elastic collisions…

A

total KE before = total KE after

27
Q

inelastic collisions:

A

total KE before > total KE after