IB Physics SL Definitions

A measurement is said to be precise if it has little random errors

A measurement is said to be precise if it has little random errors

Precision

A measurement is said to be accurate if it has little systematic errors

Accuracy

A random error, is an error which affects a reading at random.

Random Errors

A systematic error, is an error which occurs at each reading.

Systematic Errors

use least # of sig figs

Sig Figs (x or /)

use least # of decimal places

Sig Figs (+ or -)

A scalar quantity has only magnitude.

Scalar

A vector quantity has both direction and magnitude. Ex. Displacement, Velocity, Force

Vector

the change in position of an object, as a vector (magnitude and direction). unit: meters

Displacement (Topic 2)

how far an object travels in a given time; rate of change of distance, a scalar. unit: ms⁻¹

Speed

speed in a particular direction, a vector. unit: ms⁻¹

Velocity

rate of change of velocity (with time), a vector. unit: ms⁻²

Acceleration

the force placed on a moving object opposite its direction of motion due to the inherent roughness of all surfaces. units: newtons (N)

Frictional force

the force on an object perpendicular to the surface it rests on utilized in order to account for the body's lack of movement. units: newtons (N)

Normal force

the coefficient that determines the amount of friction. This varies tremendously based on the surfaces in contact. There are no units for the coefficient of either static or kinetic friction

Coefficient of friction

an object at rest or in motion will stay at rest or in motion unless acted upon by an external unbalanced net force

Newton's First Law of Motion

When the net force on an object is zero in all directions (i.e no linear acceleration)

Transitional Equilibrium

The net (or resultant) force acting on a body is equal to the product of its mass and its acceleration. F=ma

Newton's Second Law of Motion

The product of mass and velocity. A vector. units: kgms⁻¹

Linear Momentum

The change in momentum. A vector.

unit: kgms⁻²

also product of Force and time

unit: Ns

Impulse (2)

The momentum of an isolated system remains constant. (i.e no external force acting)

Law of Conservation of Linear Momentum

For every action on one object there is an equal but opposite reaction

Newton's Third Law of Motion

when a force moves an object in the direction of the force

Work

unit: Joules (J)

The rate of doing work (rate at which work is being performed

Power

unit: Watt or Joule/second (W or Js⁻¹)

energy an object has as a result of its motion

Kinetic Energy

unit: Joules (J)

energy that is stored in an object by its height

Gravitational Potential Energy

unit: Joules (J)

Energy is never created nor destroyed. It changes from one form to another.

Principle of Conservation of Energy

KE and momentum conserved - no mechanical energy lost

Elastic Collision

ex: pool balls, ideal gas particles

KE is not conserved, but momentum is.

Inelastic Collision

the ratio of the useful energy to the total energy transferred

Concept of Efficiency

unit: none (%)

direction is always changing therefore, so is acceleration and velocity

Centripetal motion (concepts)

The acceleration, directed toward the centre of a circle, which causes uniform circular motion

Centripetal Acceleration

The force, directed toward the centre of a circle, which causes uniform circular acceleration.

Centripetal Force

the average KE of the particle of a substance, which determines the direction of thermal energy transfer

Temperature

unit: Kelvin (K)

The lowest temperature possible. -273˚C or 0K

Absolute Zero

The non-mechanical transfer of energy between a system and its surroundings (naturally flows from hot to cold)

Thermal Energy (+equations)

equations:

Q = mL

Q = mc(Tf-Ti)

unit: Joules (J)

The energy contained in an object due to the random KE and PE of the molecules

Internal Energy

unit: Joules (J)

the state in which all parts of a system have reached the same temperature

Thermal Equilibrium

The amount of a substance that contains the same number of particles as there are atoms in 12g of Carbon-12

Mole

units: mol

The number of particles in a mole. A=6.02x10^23

Avogadro constant

The mass of 1mole of a substance

Molar Mass

units: g/mol

The amount of thermal energy (heat) required to raise the temperature of an object by 1K

Thermal Capacity

equation: C= Q / (Tf - Ti)

unit: JK⁻¹

The amount of thermal energy required to raise the temperature of 1Kg or a substance by 1K

Specific Heat Capacity

equation: c = Q / m(Tf-Ti)

unit: Jkg⁻¹K⁻¹

specific heat is per unit mass, so thermal is the same as specific heat, multiplied by mass

Difference between Thermal and Specific Heat Capacity

Solid-liquid

Melting

Liquid-solid

Fusion

Liquid-gas

Vaporization

boiling takes place throughout the liquid and always at the same temperature, evaporation takes place only at the surface of the liquid and can happen at all temperatures

Difference between boiling and evaporating

Gas-liquid

Condensation

Solid-gas

Sublimation

Because the energy is being used to break or make bonds and so the energy is not turned into kinetic energy.

Why does temp. not change during phase change?

the amount of energy required to change the state of 1kg of a substance

Specific Latent Heat (+formula)

formula:

Q = mLf

Q = mLv

unit: Jkg⁻¹

The force exerted per unit area

Pressure

unit: Pascals (Pa)

as Temperature increases, Pressure increases

Pressure and Temperature relationship

directly proportional so P/T = constant

as Volume decreases, Pressure increase (as particles hit the container wall more frequently)

Pressure and Volume relationship

inversely proportional so P x V = constant

as Volume increases, Temperature increases

Volume and Temperature Relationship

directly proportional so V/T = constant

P1V1T2 = P2V2T1 (# of molecules kept constant)

Combined Gas Laws (not Molecular)

or (P1V1)/T1 = (P2V2)/T2

PV = kNT (N = number of molecules, T temp in K)

Molecular Gas Law

a gas that obeys all gas laws at any pressure, volume or temperature

Ideal Gas

formula: PV = nRT (n=number of moles)

PV = nRT (n = number of moles, T in K)

Ideal Gas Law

F) no Forces act between the particles (stay in continous random motion) - Internal Energy = KE (no PE)

Kinetic Molecular Theory (FPICS)

P) there is not loss in KE between particles and the container so all collisions are Perfectly elastic

I) all particles are Identical

C) all particles remain in Continuous random motion

S) there are many particles and they are extremely Small compared to the distance between each other

1. force or acceleration is always directed towards the centre

Simple harmonic motion (SHM) factors and equation

2. the force or acceleration is proportional to the distance from the centre

defining equation: a = -w²x

Distance from the equillibrium

Displacement (Topic 4)

unit: m

The maximum value for displacement from the mid point.

Amplitude

unit: m