Linear motion Flashcards

1
Q

scalar quantity

A

when measurements are described in terms of their size and magnitude

speed + distance

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2
Q

vector quantity

A

when measurements are described in terms of magnitude (size) and direction

weight
acceleration
displacement
velocity
momentum

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3
Q

mass

A

the quantity of matter the body possesses
mass x gravity=weight

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4
Q

distance

A

length of a path a body follows when moving from one position to another

distance=speedXtime

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5
Q

displacement

A

measured in metres and is the shortest route in a straight line between the starting and finishing position

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6
Q

speed

A

the rate of change of position
speed =distance/time

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7
Q

velocity

A

measured in meters/ second and is the rate of change of displacement

displacement/ time taken

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8
Q

distance time graph

A

shows distance travelled over a period of time

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9
Q

the gradient of a graph

A

changes in y axis/ changes in X axis

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10
Q

velocity time graphs and speed time graphs

A

indicate velocity or speed of performer or object per unit of time

gradient will help decide wether the performer is travelling at a constant velocity, accelerating or decelerating

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11
Q

acceleration

A

rate of change of velocity

measured in m/s2

when velocity increases, so does acceleration

change in velocity/time

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12
Q

momentum

A

mass x velocity

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13
Q

force

A

changes a body’s state of motion

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14
Q

external force

A

comes from outside the body

friction, air resistance, weight, gravity

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15
Q

internal force

A

applied when our skeletal muscles contract

e.g. quadriceps contract concentrically to extend the knee in a jump

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16
Q

Vertical forces:
weight

A

the gravitational force exerted on an object

weight= mass x acceleration

17
Q

vertical forces:
reaction force

A

occurs when two bodies are in contacts with one another

newtons 3rd law: for every action, there is an equal and opposite reaction

18
Q

friction

A

occurs when two or more bodies are in contact with one another

19
Q

horizontal forces:
frictional force

A

static friction force:
the force exerted on one surface by another when there is no motion between the two surfaces
occurs before an object begins to slide (move)

sliding frictional force:
two bodies in contact with one another that may have a tendency to slide over each other.

20
Q

factors affecting friction

A

surface characteristics of the two bodies in contact
e.g. sprinter wearing spikes increases friction

temperature of surfaces
e.g. sweeping action in curling increases temp and reduces friction

mass of objects
a larger mass has greater fricton

21
Q

horizontal forces:
air resistance

A

a force that acts in the opposite direction to the motion of a body travelling through the air

22
Q

air resistance depends on

A

the velocity of the moving body
the faster the movement, the greater the resistance

the cross sectional area of the moving body
the larger, the greater
e.g. cyclists crouch low to reduce air resistance

the shape and surface of a moving body
a streamlined shape has less resistance. so does a smooth surface
e.g. swimmers shave their body (reduce ‘drag’)

23
Q

net force

A

resultant force acting on a body when all other forces have been considered

24
Q

a balanced force:

A

when two or more forces acting on a body are equal in size but opposite in direction
e.g. when standing, weight force and reaction force are equal but in opposite directions so there is zero net force and no change in the state of motion

25
Q

an unbalanced force:

A

force acting in one direction on a body is larger than a force acting in the opposite direction
e.g. when jumping, the reaction force is bigger than the weight force as the performer is accelerated into the air

26
Q

impulse

A

force x time

time taken for a force to be applied to an object or body

newtons second law:
an increase in impulse will result in an increase in momentum and a change in velocity

can be used to add speed to a body or slow one down on impact

27
Q

net impulse

A

a combination of positive and negative impulses