physics term 2 Flashcards
standard international units of measurements for length, mass and time
length- m
mass- kg
time- s
scalar quantity definition and example
scalar quantity has only one size
example- distance of 12km
vector quantity definition and example
vector quantity has size and direction
example- velocity of 30km/h north
what vectors go with these scalars distance speed mass time
scalar vector distance-displacement speed-velocity mass-acceleration time-force
distance definition
length travelled in a journey between start and finish , does not include direction.
displacement definition
length between start and end point only including direction from start to finish.
both formulas for average speed
average speed = distance ------------- time or = initial speed+ final speed ------------------------------------ 2
does velocity or speed include direction
velocity includes direction.
formula for velocity
time
instantaneous speed definition
speed that a vehicle is travelling at a precise point in time.
how do you covert from m/s to km/h
multiply by 3.6
how do you convert from km/h to m/s
divide by 3.6
the slope of a graph
gradient
what are motion graphs used for
to analyse the motion of a vehicle
what does the gradient and horizontal line of a distance v time graph represent
gradient= speed of the object
horizontal line= object is stationary
formula for average acceleration
average acceleration=
time taken
terminal velocity definition
speed reached when air resistance (drag) is the weight (force of gravity)
formula for weight (w)
weight = mass x gravity w = m x g
acceleration due to gravity at earths surface (g)
(g) acceleration due to gravity =
9. 8m/s squared
resistance and what affects it
the force of an object as a result of air as it moves .
Affected by the speed and surface area.
what is w, m and g
w is weight in Newtons, N
m is mass in kilograms, kg
g is acceleration due to gravity, 9.8m/s squared
when does acceleration occur
when an object has a change in speed or a change in direction
formula for acceleration
acceleration =
time
what is force measured in
newtons, N
balanced force example and definition
no change in the state of an object’s motion
example- plane flying at a constant speed or a stationary car
unbalanced force causes and example
unbalanced force may be caused by change in speed change in direction change in shape example- accelerating bicycle
how do you find the distance on a speed v time graph
calculate the area under the graph
what does the horizontal line on a speed v time graph represent
continuous speed, sitting on one speed
how do you find the acceleration of a vehicle from a speed v time graph
calculate the gradient
in the formula for acceleration, what does v, u and t stand for and what is each measured in
t
v is final velocity in m/s
u is initial velocity in m/s
t is the time in s
triangle equation for distance
d
s t
triangle equation for force
f
m a
formula for final speed
final speed = 2 x average speed
state newtons first law of motion
A body will remain at its current state of motion until and unbalanced force acts upon it.
inertia definition and what affects it
the tendency of a body to remain at its current state of motion
affected by mass. the greater the mass of a body, the more inertia
state newtons second law of motion
a body will accelerate in proportion to the net force upon it and the mass of the body
what does a greater net force result in
greater acceleration
state newtons third law of motion
two examples
for every action force there is an equal and opposite reaction force.
fire extinguisher- gas is fired out and person holding the extinguisher is pushed back
punch- fist hits object and object hits fist with same force
net force
force exerted by a body after all the forces have been added
list some safety features that modern cars are engineered with
crumple zones
seatbelts
airbags
anti-lock braking
define mass what what it is measured in
amount of material in an object, kg
weight and what it is measured in
force due to gravity acting on a mass, Newtons, N
triangle equation for weight
weight
mass gravity
define friction
the force that acts to prevent motion or acts in the opposite direction to that of a moving object
three types of friction
static
kenetic
drag
examples of when you want to reduce friction
downhill skiing
running
swimming/diving
ice skating
examples of when you want to increase friction
mountain climbing
running (spikes on boots)
parachuting
potential energy
form of stored energy
may be stored in the from of chemical, electrical, elastic or nuclear energy
gravitational potential energy
GPE is the energy due to an objects height.
higher gravitational field means more potential energy
formula for GPE
m x g x h
law of conservation of energy
energy cannot be created of destroyed, only converted from one form to another.
formula for kenetic energy
genetic energy = 1/2 x m x v squared
