Mechanics Need To Know For NCEA Flashcards
V=
speed measured in (ms-1)
t=
time measured in (s)
d=
distance measured in (m)
△=
delta=change in…..
Fnet
Net force measured in (N)
N=
Newtons
m=
mass measured in (kg) OR meters
P=
Pressure measured Pa or N/㎡ OR Power measured in (W)
Pa=
Pascals
A=
Area measured in (㎡)
△Ep=
gravitational potential energy measured in (J)
g=
gravity/10ms−² (ms squared to the negative 2)
Ek=
Kinetic energy measured in (J)
W=
Work measured in (J)
F=
Force measured in (N)
Fg=
Weight
How do you write an Energy Chain?
You use arrows (Ek→△Ep)
What are the three ways used to describe motion?
STATIONARY, CONSTANT SPEED, ACCELERATION
When calculating what are the six steps?
- State given: d=2m, v=3ms-1, t=?
- Copy formula: v=△d/△t
- Substitute: 3=2/△t
- Re-arrange (if required)
- Calculate and ROUND (2 or 3 significant figures)
- Write UNIT
When explaining what are the 4 steps?
- Write appropriate formulas
- State definitions
- Comment one each QUANTITY/LETTER (e.g SAME, INCREASES/LARGER, DECREASES/SMALLER)
- Answer the question
Can you multiply the Force and distance together if they are not parallel?
No F&d must be parallel for you to be able to multiply them together.
What is the rule of energy?
Conservation of energy (cannot be created or destroyed only transferred) HEAT (waste) caused by FRICTION and DRAG.
Definition of Mass=
The number of particles/matter in an object measured in (kg).
Definition of Weight=
A downwards force measured in (N).
What are the 6 forces?
- Weight
- Support
- Thrust (engines)
- Friction, drag/air resistance
- Lift (plane)
- Push/pull
What is the formula for weight?
Fg=mg
What direction does the force weight act?
↓ It is a downwards force (90° to the surface)
What direction does the force support act?
↑ It is an upwards force (90° to the surface)
What direction does the force thrust act?
forward (from the motion occurring)
What direction does the forces friction, drag/air resistance act?
Opposite to the motion (v) (opposite to the speed)
What direction does the force Lift act?
↑ An upwards force which acts 90° to the surface
What direction does the forces Push/Pull act?
from/to the centre (of the motion)
When the motion is stationary or constant speed are the forces BALANCED or UNBALANCED?
They are BALANCED.
When the motion is stationary or constant speed what is the net force?
The NET FORCE is ZERO
When the motion is accelerating are the forces BALANCED or UNBALANCED?
The forces are UNBALANCED
When the motion is accelerating what is the NET FORCE?
NET FORCE is NOT ZERO (it is in the direction of accelerating). (net force & acceleration are the same direction)
What is △Ep?
Height
What is Ek?
Speed
What is △E=W
The definition of Work (change in Energy=Work)
What are the 2 graphs used in Mechanics?
d&t (distance & time) and v&t (speed & time)
Which axis is time always on?
The x axis (bottom horizontal line)
What is a distance versus time graph used to work out?
The Speed of something.
On a distance versus time graph how do you find the speed?
gradient=steepness=SPEED=rise/run (rise over run)
What does 〳 (a curved upwards line) mean on a distance versus time graph?
ACCELERATION
What does / mean on a distance versus time graph?
CONSTANT SPEED
What does _ mean on a distance versus time graph?
STATIONARY
What is a speed versus time graph used to work out?
The ACCELERATION of something
On a speed versus time graph how do you find the Acceleration?
gradient=steepness=ACCELERATION=rise/run (rise over run)
What does / mean on a speed versus time graph?
Accelerating
What does _ mean on a speed versus time graph?
Constant speed
How do you find the distance on a speed versus time graph?
You find the area of the sections.
How do you find the area of a square?
b×h (base times height)
How do you find the area of a triangle?
½b×h (half base times height)
What is v=△d/△t and what is it used to work out?
Speed equals change in distance over change in time. It is used when working out the speed of something. It is the partner of distance versus time graphs.
What is a=△v/△t and what is it used to work out?
Acceleration equals change in speed over change in time. It is used to work out the acceleration of something. It is the partner to speed versus time graphs.
How do you define acceleration?
a=△v/△t, gradient=steepness=ACCELERATION=rise/run.
ms–² (ms to the power of negative two.)
Acceleration
ms-1 (ms to the power of negative one)
Speed
m²
metres squared
N/m² (N over m²) is another way to measure?
Pressure. Pressure can be measured in Pascals or N over m squared.
What is Fnet=ma and what is it used to work out?
Net force equals mass times acceleration. Used to work out the forces acting on an object
What is this symbol (ΣF)?
The sum of the forces (ΣF)
What does Fnet mean
The sum of all the forces
What is P=F/A (P=F over A) and what is it used to work out?
Pressure=Force times Area. Used to work out what pressure is being applied to something by something.
What is △Ep=mg△h and what is it used to work out?
Change in gravitational potential energy=mass times gravity times change in height. Used to work out the height something has (dropped).
What is Ek=½mv² and what is it used to work out?
Kinetic energy. Used to work out the movement of something.
What is W=Fd and what is it used to work out?
Work=Force times distance. Used to work out the amount of Work done on something.
What is g=10Nkg-1 (squared to the negative one) and what is it used to work out?
Gravity and it always stays the same.
What is P=W/t (W over t) and what is it used to work out?
Power=Work divided by time. Power is the measurement of how quickly Work is done.
What do you use to work out the speed of something from the middle of the graph?
Vend or Vbeginning.
How can the starting Kinetic energy be lower at the end than at the start?
Due to waste energies such as heat, sound and light.
On a speed versus time graph how do you find the distance?
Area. The distance travelled is the area under the line.
