physics Flashcards
9.1-9.4
what is distance?
distance is the length between 2 points or objects
what is speed?
speed is a measure of how fast something moves.
what is average speed?
a measure of how fast something moves overall
what is instantaneous speed?
speed at a particular instant, eg stopping or speeding
converting units
1km/1hr = 1000m/60min = 1m/3.6s
speed calculations
speed = distance/time
distance=speedxtime
time= distance/speed
(memorise the triangle if it helps)
d
s t <———- the triangle
what is acceleration?
rate at which an object changes its velocity (velocity means a speed of something in a particular direction)
what is terminal velocity?
the constant speed that a free falling object eventually reaches when the resistance of the medium through which it’s falling prevents further acceleration
examples of acceleration
-driving a car and slowing down and speeding up during turns
-someone sprinting after stopping
average acceleration formula
average acc. = change in speed/ time
↓
=final speed-initial speed/time
OR
a=v-u/t
final speed formula
final speed=initial speed+(average acc+time)
OR
v=u(a+t)
what is a speed time graph?
a speed time graph shows an objects speed changes over time
an object speed may
-be constant (_____ line)
- increase (graph_______ _________)
-decrease (graph _________ __________)
a. flat
b. rising upwards
c. falling downwards
slope of speed-time graphs =?
acceleration
area of speed-time graphs=?
distance
distance of st graph (hints)
u can use area of ______
eg. triangle (_____) or square (______)
a. shapes
b. 1/2 bh
c. length x breadth
LEARN AREA FORMULAS ESPECIALLY TRIANGLES AND RECTANGLES
acceleration of st graph (hints)
have to use _____
eg. 5/2 = 2.5____
a. rise/run
b. m/s²
DO NOT FORGET TO WRITE UNITS
what did galileo galilei discover?
he discovered that objects stop because the force of friction acts in the opposite direction to their motion.
what is newtons first law of motion?
newtons first law of motion states that an object at rest will stay at rest unless acted upon by an unbalanced force.
(this law applies to motion as well, just replace ‘rest’ with ‘motion’)
expand on the first law of motion using a moving object
an object that is moving will continue to move in the same direction and speed unless that object is acted upon by an unbalanced force.
what is inetria?
the tendency to resist any change in motion is an objects inetria.
how does mass have an effect on inertia?
the larger the mass of an object, the greater its inertia, the harder it is to change it’s motion
what could unbalanced force change?
-speed
-direction
-state
-motion
RANDOM QUESTION!!!!!!
what is support
support is the upward force of an object (n)
what is newtons second law of motion
an object will accelerate in the direction of an unbalanced force acting upon it.
what does the size of the acceleration depend on?
it depends on the mass of the object and the size of the force acting upon
a _______ force is needed to __________ a _________ load
a. larger
b. accelerate
c. heavier
what is required to make an object accelerate faster?
a larger force is required for on object to accelerate at a faster rate
formula for newtons second law of motion
f(net) = m x a
how many forces are acting on an object at one time?
usually more than one
acceleration formula (to find acceleration from f(net))
a = fnet/m
what is newtons third law?
for every action force, there is an equal and opposite reaction force
the acceleration that an object experiences due to a force depends on…
its mass
an object with low mass will travel with much _______ acceleration than a more massive object
greater
what is kinetic energy
the energy of a moving object is called kinetic energy
the amount of kinetic energy an object has depends on…
its mass and speed
object mass doubles = kinetic energy _____
doubles
object speed doubles = kinetic energy _______________
increases by a factor of 4
kinetic energy formula
KE = 1/2mv²
what is potential energy?
potential energy is the energy that an object has because of its position or structure.
EXTRA
this gives objects the capacity to make things happen
how does an object have gravitional potential energy?
if an object is positioned above the ground that means it has gravitational potential energy
the greater the mass the _______ its gravitational potential energy will be
greater
what has elastic potential energy?
a stretched or compressed object (most likely a spring) has elastic potential energy
what is the law of conservation of energy?
energy may be transferred or transformed but it is never created or destroyed
explain energy efficiency
some energy may be ‘lost’ because it changes into non-useful form such as heat and sound.
the energy used is referred to as ____________
input
using the diagram below, identify the input, useful energy and non useful energy for a DRILL)
electrical energy –> kinetic energy + sound energy + heat energy
input - electrical energy
useful energy - kinetic energy
non-useful energy - heat energy + sound energy
efficient energy formula
useful energy output/ total energy output x 100%
