Revision resources...click below...
NZQA Mechanics Examination Papers..click below..
These are worth checking out !!!
motion_notes.ppt  
File Size:  228 kb 
File Type:  ppt 
Motion this is the "way" something is moving an object is in motion if its position is changing...
Characteristics of motion are:
Objects have a speed, they travel a distance, have direction and could be accelerating or slowing down (decelerating).
When describing the motion of an object like a car we use quantities like time, distance , speed and acceleration.
Characteristics of motion are:
Objects have a speed, they travel a distance, have direction and could be accelerating or slowing down (decelerating).
When describing the motion of an object like a car we use quantities like time, distance , speed and acceleration.
SPEED and VELOCITY
SPEED  is the "rate" at which an object is moving.
To calculate Speed we use the equation: SPEED = DISTANCE / TIME
Because most times the direction of the object is always given we use Velocity as our Speed. Velocity is speed in a particular direction.
Average Speed  is a measure of distance traveled each hour, min or second. The average speed (v) for a journey is calculated from the TOTAL distance travelled divided by the TOTAL time taken
SPEED  is the "rate" at which an object is moving.
To calculate Speed we use the equation: SPEED = DISTANCE / TIME
Because most times the direction of the object is always given we use Velocity as our Speed. Velocity is speed in a particular direction.
Average Speed  is a measure of distance traveled each hour, min or second. The average speed (v) for a journey is calculated from the TOTAL distance travelled divided by the TOTAL time taken
We can rearrange the formula's above to find distance OR time.
Instantaneous Speed  is the actual speed at any moment  for example if you looked down at the speedometer whilst travelling in the car  the speed at that particular instant in time would be termed the instantaneous speed of that object  it will usually change considerably during a car's journey.
If it does NOT change then that objects speed is termed constant, uniform or steady !
DISTANCE  TIME GRAPHS:
These tell us about an objects type of SPEED !!!!
These graphs plot the objects journey from start to end point.
They can be used to calculate the average speed AND the SLOPE of the graph also gives us information about the objects type of motion/speed !!
Check out the video below


DistanceTime Graph Interpretation:
Calculating the SPEED using a DISTANCETIME Graph .....
The GRADIENT or SLOPE of a DT graph tells us about the objects SPEED in ms1
To calculate the speed we use rise/run or Distance/Time.
We must be careful to only calculate the speed for the section asked  so check values carefully in questions!!
The GRADIENT or SLOPE of a DT graph tells us about the objects SPEED in ms1
To calculate the speed we use rise/run or Distance/Time.
We must be careful to only calculate the speed for the section asked  so check values carefully in questions!!
The average speed can be calculated for any part of a journey by taking the change in distance and dividing by the change in time for that part of the journey. You can even do this for a curved line where the speed is changing, just remember that your result is the average speed in this case. You may also notice that the formula for calculating speed is sometime written with small triangles Δ (the Greek letter delta) in front of d (distance) and t (time). The Δ is just short hand for "change in". Therefore Δt means "change in time"
DESCRIBING THE MOTION OF AN OBJECT.......
When describing the motion of an object try to be as detailed as possible. For instance...

DECELERATION:
When an object speeds up we say it is accelerating. When an object is slowing down we say it is decelerating.
NB:
When we explain about an object slowing down...... we can explain it in one of "2 ways"....
1. The care is decelerating at 2 ms2
OR
2. The car is accelerating at  2 ms2 (note the  before the units)
Choose one way and stick with it !
When an object speeds up we say it is accelerating. When an object is slowing down we say it is decelerating.
NB:
When we explain about an object slowing down...... we can explain it in one of "2 ways"....
1. The care is decelerating at 2 ms2
OR
2. The car is accelerating at  2 ms2 (note the  before the units)
Choose one way and stick with it !
ACCELERATION
A change in the speed of an object is called its acceleration
It can be defined as the RATE at which the velocity (speed) of an object changes in a certain time ie: per second.
When an object speeds up we say it is accelerating  when an object slows down we say it is decelerating.
Unit is  MS2
How do you calculate the "change in speed"???  you can use the equation  V final  V initial (starting speed)
A change in the speed of an object is called its acceleration
It can be defined as the RATE at which the velocity (speed) of an object changes in a certain time ie: per second.
When an object speeds up we say it is accelerating  when an object slows down we say it is decelerating.
Unit is  MS2
How do you calculate the "change in speed"???  you can use the equation  V final  V initial (starting speed)


Calculating the TOTAL DISTANCE traveled from a SPEEDTIME graph ?
The total distance traveled in a journey is represented by the AREA under the vt graph The way to calculate this is to break your graph up into "shapes" and find the area of each shape (just like you would do in Maths) so AREA = DISTANCE TRAVELLED The area under the line in a velocitytime graph represents the distance travelled. To find the distance travelled in the graph above, you need to find the area of the lightblue triangle and the darkblue rectangle.

FORCES:
Forces are a push, pull or a twist.
A Force is something which will change the motion of an object. A Force applied to an object may change the objects speed, direction or shape !
(If the force causes an object to speed up = accelerate or slow down = decelerate)
Forces act on everything !!! Often there is more than one force acting on an object. When this happens it is the resulting combination of all the forces acting that will affect the MOTION.
The Resultant force is called the Net Force  F net . Forces acting in the same direction are added together  forces acting in opposite directions are subtracted and the difference/result becomes the NET FORCE !
A FORCE F  has both a size and direction. The size of the force is measured in Newtons N and the direction of the force is shown with an arrow !
When all the forces acting on an object are BALANCED  then the Net Force is zero. If the object is already moving then it will move at at CONSTANT speed. If it is not moving then it will remain STATIONARY.
When forces acting on an object are UNBALANCED  there is a NET FORCE acting and the object will ACCELERATE and DECELERATE  in the direction of the Net Force!
AIR RESISTANCE:...how does this work ?
Forces are a push, pull or a twist.
A Force is something which will change the motion of an object. A Force applied to an object may change the objects speed, direction or shape !
(If the force causes an object to speed up = accelerate or slow down = decelerate)
Forces act on everything !!! Often there is more than one force acting on an object. When this happens it is the resulting combination of all the forces acting that will affect the MOTION.
The Resultant force is called the Net Force  F net . Forces acting in the same direction are added together  forces acting in opposite directions are subtracted and the difference/result becomes the NET FORCE !
A FORCE F  has both a size and direction. The size of the force is measured in Newtons N and the direction of the force is shown with an arrow !
When all the forces acting on an object are BALANCED  then the Net Force is zero. If the object is already moving then it will move at at CONSTANT speed. If it is not moving then it will remain STATIONARY.
When forces acting on an object are UNBALANCED  there is a NET FORCE acting and the object will ACCELERATE and DECELERATE  in the direction of the Net Force!
AIR RESISTANCE:...how does this work ?
Mass and Weight
MASS is a measure of how much "matter" there is in an object. Mass remains the same even if the location does not ie: our mass it the same on earth as it would be on Mars.
Symbol m
Units  Kg or g
WEIGHT  is the downward force due to gravity on any mass !
it is a measure of the mass plus the force of gravity acting on that object. (weight is a measure of the force acting on an object caused by the force of gravity. )
So weight is a force !
Symbol  Fnet
Units is  N
The force of gravity pulls a 1 kg mass with a force of 10 Newtons  this is written as The Force of Gravity =10Nkg1
Any object that is dropped will accelerate towards the center of earth at approximately 10 m per sec for every second it is falling (10 ms2 ) or alternatively 10 N of force for every kg (10Nkg1)
If we are given the mass of an object we can work out its weight force /F net by multiplying it by 10.
Eg: Zack is mountain biking down the Barnicoat. His total mass is 80 kg (him and bike together) Calculate the weight due to acceleration down the hill.
F net = m x g
= 80 kg x 10 N kg1
F net = 800 Kg
When we get scenarios with STAIRS, HILL's or LIFTING....this probably requires us to use the f= m x g in order to find the force as the first step 1 the working out !!! Then we can use the F = m x a equation.
MASS is a measure of how much "matter" there is in an object. Mass remains the same even if the location does not ie: our mass it the same on earth as it would be on Mars.
Symbol m
Units  Kg or g
WEIGHT  is the downward force due to gravity on any mass !
it is a measure of the mass plus the force of gravity acting on that object. (weight is a measure of the force acting on an object caused by the force of gravity. )
So weight is a force !
Symbol  Fnet
Units is  N
The force of gravity pulls a 1 kg mass with a force of 10 Newtons  this is written as The Force of Gravity =10Nkg1
Any object that is dropped will accelerate towards the center of earth at approximately 10 m per sec for every second it is falling (10 ms2 ) or alternatively 10 N of force for every kg (10Nkg1)
If we are given the mass of an object we can work out its weight force /F net by multiplying it by 10.
Eg: Zack is mountain biking down the Barnicoat. His total mass is 80 kg (him and bike together) Calculate the weight due to acceleration down the hill.
F net = m x g
= 80 kg x 10 N kg1
F net = 800 Kg
When we get scenarios with STAIRS, HILL's or LIFTING....this probably requires us to use the f= m x g in order to find the force as the first step 1 the working out !!! Then we can use the F = m x a equation.
AIR RESISTANCE:...how does this work ?
Watch the you tube clip opposite.... 

PRESSURE:
This is how much Force is put into a particular area. So the amount of pressure depends of 2 things.
The EQUATION we use for Pressure is:
This is how much Force is put into a particular area. So the amount of pressure depends of 2 things.
 The FORCE in Newtons ( N )
 The AREA its pressing on ( the contact area) in square metres m2 (squared)
The EQUATION we use for Pressure is:
Kinetic Energy:
This is the type of Energy all MOVING objects have !
See equation AND Units below...
Things to remember:
If the mass is bigger then the Kinetic E will be Bigger
If the Speed is bigger then the Kinetic E will be bigger
If the Mass is doubled (speed same) then the Kinetic E will be doubled.
Altering the velocity of an object has a squared effect on its kinetic energy. For instance doubling the velocity will quadruple the kinetic energy. Tripling the velocity will give the object nine (three squared) times as much kinetic energy
This is the type of Energy all MOVING objects have !
See equation AND Units below...
Things to remember:
If the mass is bigger then the Kinetic E will be Bigger
If the Speed is bigger then the Kinetic E will be bigger
If the Mass is doubled (speed same) then the Kinetic E will be doubled.
Altering the velocity of an object has a squared effect on its kinetic energy. For instance doubling the velocity will quadruple the kinetic energy. Tripling the velocity will give the object nine (three squared) times as much kinetic energy
GRAVITATIONAL POTENTIAL ENERGY:
This is the Energy stored in an object whenever you lift or swing that object.
The object gains whatever the energy was, that was needed to move it ie: it is often referred to as the energy an object has because of its "position".
If you have to do work on an object, then energy gets stored on/in it
 Eg: you lift a suitcase off the floor onto the bed  you do work against the force of gravity so the suitcase gains Gravitational Potential Energy. You move it off the bed back onto the floor  it loses Gravitational Potential energy (that is had gained)
WORK
In science WORK has a special meaning and defined as "the amount of Energy transferred"
It is also often explained as the "ability to do work".
WORK is DONE (ie: energy is transferred) if a object is MOVED over a set distance in the direction of the Force.
So the equation we use:
WORK = FORCE x DISTANCE W = F x D
Unit is Joules
When WORK is done Energy is transferred  the "thing" doing the work loses E and the "thing" having the work done gains the Energy.
In science WORK has a special meaning and defined as "the amount of Energy transferred"
It is also often explained as the "ability to do work".
WORK is DONE (ie: energy is transferred) if a object is MOVED over a set distance in the direction of the Force.
So the equation we use:
WORK = FORCE x DISTANCE W = F x D
Unit is Joules
When WORK is done Energy is transferred  the "thing" doing the work loses E and the "thing" having the work done gains the Energy.

