1/99
Name | Mastery | Learn | Test | Matching | Spaced |
---|
No study sessions yet.
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
closed sytem
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 (no resultant torque), 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
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.
decimal places of a metre ruler/ruler
1 d.p. in cm
decimal places of a micrometer
2 d.p. in mm or 2d.p in cm
decimal places of a stopwatch
2d.p in seconds
Energy
the ability to do work
Law of Conservation of Energy
Energy can neither be created nor destroyed but it can change from one form to another (transformed or transferred
Types of Energy
Kinetic Energy
Gravitational potential energy
Electrical energy
Sound Energy
Light Energy
Elastic potential Energy
Nuclear Energy
Chemical potential energy
Thermal Energy
Chemical potential energy(stored)
stored in the chemical bonds within substances such as fossil fuels, bio gas, carbohydrates and fats
elastic potential energy (strain)(stored)
stored in an object whose shape has been changed in s reversible way, such as a stretched or comppressed spring.
gravitational potential energy(stored)
stored in a system die to the gravitational field between two objects
kinetic energy(stored)
stored in moving objects
nuclear energy(stored)
stored in the nucleus of every atom and transferred during radioactive decay, nuclear fission or nuclear fusion.
work
the transfer of energy from one form to another
Joule
the amount of work done when a force of 1 Newton moves an object a distance of 1 meter in the direction of the force
Conditions for work to be done
There has to be a force and a distance moved
Energy needs to be transferred
isolated system
conservation of energy
kinetic energy
the energy of moving objects
Gravitational potential energy
the potential energy an object has because of its height
Power
the rate of transfer of energy or the rate at which work is done
density of water
997 kg/m³
Hooke’s law
for an object under tension, the extension is proportional to the applied load, as long as the limit of proportionality is not exceeded.
spring constant (k)
determines how much force will be required to deform a spring. measure of stiffness
Limit of proportionality
Hooke’s Law does not apply past this point.
Elastic limit
The spring will behave as a plastic material and wont return to its original length when load is removed
Tensile force
causes an object to stretch/increase in length
Compressive force
causes an object to be compressed
Plastic behaviour
deforms and stays deformed when force is removed
elastic behaviour
returns to original shape when force is removed
Young modulus
a measurement for the stiffness of a material
Stress
a measurement of the tensile/compressive per unit cross-sectional area of the material
Strain
a measurement of the extension of the material as a proportion to the original length
Ultimate tensile strength
the ultimate stress a material can withstand before it breaks
Brittle
Material fractures before plastic deformation (Glass, ceramic)
Ductile
Material can withstand large plastic deformation without breaking (copper)
Polymeric
material made up of long repeating chains of molecules - no plastic deformation