Physics 1 Flashcards
What is an atom?
- Fundamental building blocks of matter
- Smallest particles into which an element can be reduced to
- contains protons, neutrons and electrons
Which sub atomic particles are responsible for the majority of mass in an atom?
- Proton
- Neutron
Which sub atomic particles can be found in the nucleus of an atom?
- Proton
- Neutron
Define an ‘element’ in terms of the kind of atoms it contains?
An element is a pure substance that consists only one type of atom
Elec charge in the following?
Neutrons - Zero / neutral
Protons - Positive
Electrons - Negative
Define the term ‘mixture’
A substance that consists of 2 or more different substances not chemically bonded and not fixed to one another in proportion
Define the term ‘molecule’
A molecule occurs when 2 or more atoms are chemically bonded together
Define the term ‘compound’
A substance consisting of 2 or more chemically bonded and fixed ratio chemicals
Describe the states of matter
- Solid
- Liquid
- Gas
- Plasma
Explain how atoms can be electrically neutral?
A standard atom will have the same number of protons and electrons. The equal number of +ve and -ve charges act to cancel each other out - therefore becoming zero elec charge
How is a solid characterised?
- Molecules are close together
- Have definite volume and shape
- Incompressible
How are liquids characterised?
- Molecules are further apart (than solids)
- Molecules do not maintain regular pattern
- Easily move into shapes
- Have definite volume
- Will flow to the lowest possible position, due to gravity
- Are slightly compressed
- Conform to shape of container that are placed in
How is a gas characterised?
- Added more heat makes the particles move faster
- Molecules are much further apart (than liquids and solids)
- They space themselves out to fit whatever space they are put into
- Does not hold a fixed shape
What is the process called when changing from solid to liquid?
Melting
What is the process called when changing from liquid to gas?
Evaporation
What is the process called when changing from a gas to liquid?
Condensation
What is the process called when changing from liquid to solid?
Freezing
What is the process called when changing from liquids to gas?
Vaporisation or evaporation
Define density?
Density is defined as the amount of space a substance takes up compared to its mass
Define compressability?
Compressibility is defined as the change in volume for applied pressure
Define surface area?
The property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of its molecules
Define specific gravity
Density of a substance compared to the density of a substance as a known reference, measures as a ratio therefore no units
How do you calculate the specific gravity of a gas?
Ratio of the density of the substance compared to NTP air
What is the definition of elasticity
The amount a substance will change its shape compared to how much force is applied
Difference between scalar and vector?
Vector - requires direction as well as distance and time
Scalar - only requires distance and time
What are some examples of scalar quantities?
- Speed
- Distance
- Time
- Temperature
- Mass
What are some examples of vector quantities?
- Displacement
- Velocity
- Acceleration
- Force
- Weight
- Momentum
How do you add vectors?
Joining the tail of the first arrow with the arrow of the second
Newtons first law?
“A body at rest tends to remain at rest, a body in motion tends to remain in motion - unless an outside force acts upon it”
- Refers to inertia
One word used to explain Newton’s first law?
Inertia
Newton’s second law?
“The acceleration of a body is directly proportional to the force causing it, and inversely proportional to the mass of the body”
Equation for Newtons second law?
Force = mass x acceleration
Newton’s third law?
“For every action there is an equal and opposite reaction”
What does inertia cause mass to resist?
Directional change
Linear / translational motion - where does the force have to act from?
Centre of mass
How do you get rotational motion?
Circular motion of an object about a FIXED AXIS
What relationship does rotational motion depend on?
Between the angle of rotation and angle of velocity
Unit used for force?
Newton metres (N)
What happens to a stationary object when the force is applied to it?
Acceleration
Difference between mass and weight?
Mass - measure of amount of matter it contains
Weight - Force exerted on a body by the gravitational force of earth
What happens to a moving force when a force is applied in the opposite direction?
Deceleration
Defining properties of mass?
- Amount of material in body
- Measured by comparison of known mass
- Constant everywhere
Defining properties of weight?
- Force
- Measured using spring balance
- Vary considerably depending on where the body is related to other larger masses
Formula for weight?
Weight = mass x gravity
What is the magnitude of acceleration due to gravity?
9.8MS
Do objects always accelerate at 9.8ms squared in a uniformed gravitational field?
- Air resistance plays a role in this, the acceleration of gravity will not be realised due to drag and friction
Ways to increase an objects stability?
- Lower centre of gravity
- Widen base
How is centre of gravity determined in an aircraft?
Datum
What is normal reaction force?
Force moving upwards to resist gravity
When an object is stationary on a bench, what is the magnitude and direction of the normal reaction force?
- Upwards
- Equal to the mass of the object
3 types of friction?
- Static
- Dynamic / kinetic
- Rolling
What is the equation for the co-efficient of friction?
Resistive friction / Normal reaction force