Phys Vocab

magnitude

size of a quantity

homogeneity

The SI unit must be the same on both sides of the equation

Random error

not predictable or constant, caused by human ability,

parallex error

not being at eye level and reading the scale wrong, can be averaged out

Systematic error

Occur due to faulty equipment , cannot be averaged out.

Absolute Uncertainty

+-(1/2 x resolution of measuring equipment)

percentage uncertainty

absolute uncertainty/measurement x 100

absolute uncertainty (repeats)

+-(1/2 x range of readings)

add absolute uncertainties

Adding/subtracting uncertainties

add percentage uncertainties

Multiplying/dividing uncertainties

Multiply percentage/fractional uncertainty by power

Raising to a power

High random errors

large range of measurements (accurate, not precise)

Systematic errors

peak of the graph displaced to the left or right (not accurate, precise)

resolution

the smallest change in the quantity being measured (input) of a measuring instrument that gives a perceptible change in the reading

scalars

Have a magnitude and a unit

length, area, volume, speed, mass, density, pressure, temperature, energy, entropy, work, power.

Vectors

Have a magnitude. unit, and a direction

displacement, velocity, acceleration, momentum, force, lift, drag, thrust, weight.

Distance

How many meters an object has moved while changing positions (scalar)

displacement

length of the gap between two points (vector)

relative velocity

the velocity of an object in relation to another

Vector components

The components (usually horizontal and vertical) of a Vector

SI base units

Elcectrical current (A), thermodynamix temperature (K), time (s), length (m), mass (kg), Luminous intensity (cd), amount (mol)

10^12

tera (T)

10^9

giga (G)

10^6

mega (M)

10³

kilo (k)

10^-1

deci (d)

10^-2

centi (c )

10^-3

milli (m)

10^-6

micro upside down n

10^-9

nano (n)

10^-12

pico (p)

Suvat equation (no initial velocity)

s = vt - ½at²

mass

The property of an object that resists a change in motion. The amount of matter in a substance

weight

the effect of a gravitational force on an object

Newton’s first law

An Object remains at rest or continues to move with a constant speed unless acted upon by a resultant force

Inertia

The Resistance to motion that an object has because of its mass

transational equillibrium

all forces on an object are balaced

Newtons second law

If an object experiences an external net force, it will accelerate such that F(net) = ma

equation for momentum(p, kgms^-1)

mass(m, Kg) x velocity (v, ms^-1)

momentum

a measure of how difficult it is to stop a moving object

Impulse

the change in momentum of an object when a force acts on it

Impulse (Ns) equation

mv - mu (mass x velocity- mass x initial velocity)

rate of change of Impulse (N)

(mv-mu)/t = F

Newtons third law

When an object exerts a force on a second object, the second object simultaneously exerts a force of equal magnitude and opposite direction on the first object.

Friction

contact force acting when surfaces contact each other. Acts in opposite direction of motion

Drag

Resistive forces when moving through a viscous fluid

Air resitance

drag force when moving through the air

Terminal Velocity

The drag force is equal to the weight force

smaller mass means what happens to the deceleration?

makes the deceleration larger

isolated system

a coservation of momentum

one dimension

move and interact only in one straught line

elastic collision

momentum AND kinetic energy are conserved

Inelastic collision

ONLY momentum is conserved, Kinetic energy isnt.

perfectly inelastic collision example

Objects stick together

Perfectly elastic collision example

Objects move apart.

principle of moments

when clockwise and anticlockwise moments are balanced (equal), no rotation will occur

Torque

the turning effect of a force

Equillibrium

when the sum of all forces acting on an object and the sum of all torques acting on the object are zero

couple

Two equal and opposite forces can produce a turning effect

Centre of gravity

the single point through whic the weight of an object is considered to act

principle of moments

if there is no resultant torque on a body then it is in rotational equillibrium

uniform object

Centre of gravity in the middle of the object

Density

the mass of a substance per unit volume

Volume

The quantity of space an object takes up

Pressure

a measure of how “concentrated” an applied force is (pressure = force per unit area)

Upthrust

A n object placed in a fluid experiences an upward force from the fluid

Archimedes principle

the upthrust on a body which is either partially or fully submerged in water is equal to the weight of the water displaced by the body.