forces and motion Flashcards

1
Q

what is the difference between speed and velocity

A

velocity measures direction

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2
Q

what are the two formulas for acceleration

A

a = (v-u) / t

v2 = u2 + 2as (v2 is v squared)

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3
Q
distance-time graphs
what is 
a) gradient
b)horizontal flat line
c) sloped straight line
d) curve
A

a) gradient = speed
b) flat = no movement
c) straight slope = constant speed
d) curve = acceleration or deceleration

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4
Q
velocity time graphs 
what is 
a) gradient
b)horizontal flat line
c) sloped straight line
d) curve
e) area
A

a) gradient = acceleration
b) flat = steady speed
c) straight slope = constant acceleration
d) curve = changing acceleration
e) area = distance

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5
Q

weight mass and gravity

A

W= mg

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6
Q

what is gravity/ weight

A

a force which acts straight downwards

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7
Q

what is a reaction force

A

a force which acts perpendicular and away from a surface

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8
Q

what is an electrostatic force

A

a force between two charged objects

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9
Q

what is drag/ air resistance/ friction

A

a force which slows something down

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10
Q

how to reduce friction

A

lubricant eg water, oil, grease

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11
Q

what happens to friction as speed increases

A

friction increases

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12
Q

newton’s first law of motion

A

balanced forces mean no change in velocity

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13
Q

newton’s second law of motion

A

if there is an unbalanced force (a resultant force) then the object will accelerate in that direction

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14
Q

force mass and acceleration formula

A

F = ma

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15
Q

vectors vs scalars

A

vectors measure direction and size; scalars only measure size.

vectors: force, velocity, acceleration, momentum
scalars: mass, temperature, time, length

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16
Q

why do objects reach terminal velocity

A

The object has weight so as it falls it accelerates
There is a drag force acting upwards
As the speed increases, the drag increases
Eventually drag=weight
Constant velocity due to balanced forces
( resultant force=0)

17
Q

what is Hooke’s law

A

the extension is proportional to force

18
Q

what is elastic behaviour

A

returning to original shape once the forces are removed

19
Q

what is the elastic limit

A

the point past which the material no longer obeys Hooke’s law and will no longer return to its original shape

20
Q

what affects thinking distance

A
how fast you're going
reaction time ( influenced by tiredness, drugs, alcohol etc)
21
Q

what affects braking distance

A

how fast you’re going
mass of vehicle
friction (road surface, weather, tyres)
how good your brakes are