A momentum of an isolated system with no external forces applied on the system, will remain constant
Impulse
Change of momentum
Vectors
Work
Work involves moving a moving a force through a distance
Energy and work are scalar quantities
Energy
Potential Energy
m g h
Kinetic energy
1/2 m v^2
Conservation of energy
inital PE = final KE
PE= final KE + Q
Power
Rate at wihch energy is transformed
J S^-1 = Watt
Efficiency
Is the ratio of useful power with respect of the power receive
Eff =( Power out / Power In) * 100
Colliisions
Elastic Collision = KE is conserved
Inelastic Collision = KE is lost
Hooke´s Law
F x = 1/2 j x^2
K = N m^-1
Measurements
Units
Fundamental Units
Mass Kg
distance m
Time s
Temperature ºC
Current A
Light Intensity Cd
Derived Units
Force kg m s^-1
Power Kg m S^-3
Energy J
Velocity ms^-1
Acceleration ms^-2
Pressure F/A
Electric Charge C
Resistance Ohm
Uncertainties
Absolute
(1.57 ± 0.03)m
Relative
1.57m ± (0.03m/1.57m) = 1.57m ± 0.02
Percentage
: 1.57m ± (0.02 × 100%) = 1.57m ± 2%
Prefixes
Yotta- (Y)
Zeta- (Z)
Exa- (E)
Peta- (P)
Tera- (T)
Giga- (G)
Mega- (M)
kilo- (k)
Hecto- (h)
Hecto- (h)
Deka- (da)
deci- (d)
centi- (c)
milli- (m)
micro- (μ)
nano- (n)
pico- (p)
femto- (f)
Errors, Precision and
accuracy
Types of error
Random errors
Changes in temperature, pressure, humidity.
Different person reading the instrument
Reaction time
Malfunction of a piece of apparatus..
Malfunction of a piece of apparatus.
Systematic Errors
Computational and mathematical deficiency.
Incorrectly report raw data.
Incorrect application of theory and equations.
Precision
indicates that an instrument or method has the capacity to give the same reading of the measurement.
indicates how near is the readings to the true value of the measurement.
Circuits
Battery = Converts Chemicial PE into electric current
Electric current = The amount of charges flowing per unit time
Electric charge = positive & negative
Electric potential differene = work done to move a charge from one point to another point per unit charge.
Electron volt = Energy needed to move one electron through a p.d. of 1 v.
Resistivity= property of the material. The ability to oppose to flow of current
Resistance property of an object, the ability of an ojbect to oppose to the flow of current.
Conductors are where e free to move.
Resistance
Ohms law= the electric current through an ohmic conductor is directly
proportional to the p.d. across the conductor remaining the temperature
and other physical quantities constant
Resistance changes form conductor to conductor. Resistance increases
with temperatyr in Conductors.
Energy & Power
e.m.f. electro motive force. The chemical energy converted to electric energy per unit charge.
Potential = The electric energy converted to the thermal energy per unit charge.
Power delivered= the amount of chemical energy converted to electric energy per unit time
Power dissipated amount of electric energy converted to thermal dissipated per unit time.
Parallel & Series cicuits
Sensors
Thermistor
It is a semiconductor
Temperature increases = resistance increases
Strain Gauge
Thermal
Heat= is the process by which energy is trasferred.
Internal Energy: Is the KE and PE on the molecules of all the object.
Thermal capacity= Is the amount of thermal energy Q needed to raise the temperature of a body by 1k.
Q = C Tf-Ti
Especific Heat capacity : Is the amount of thermal energy Q needed to raise the temperature of 1 kg of a substance 1k.
Q = m C Tf- Ti
The temperature as measured on the thermodynamic scale is proportional to the average KE per partcile.
Thermal mechanisms
Convection
Conduction
Radiation
Specific latent heat = for any phase transformation (at constant temperature) is defined as the latent heat per unit mass.
Q = m L
Pressure in a Gas
Pressure is equal to the force over the unit area.
P = F/ A
If the force is greater there will be more collisions per unit time.
Waves
Oscillation
Any vibration that goes back and forward
Cycle= is one oscillation
eEquilibrium position = Where the system or object
tends to be.
Time period = The time needed for one cycle.
Frequency= number of cycles per unit time
Simple Harmonic Motion
The acceleration is directly proportional to the equilibrium point.
The acceleration is directed always to the equilibrium point.
Formula ( Beginning from the maximum positive point)
X= Xo * cos (W *t)
v = - W* Xo * sin (Wt)
a = -W^2 * x
Vo = W * Vo
Energy formulas
KE = 1/2 * m* W^2 (Xo^2-X^2)
PE = 1/2 m * W^2 * X^2
Damping
Light damping = Amplitude changes
Over Damping = Ampliitude changes drastically
Critical Damping = It does not passes from one oscillation
Forced oscillation and resonance
Natural Frequency
Forced oscillation
Resonance
Waves
Is a disturbance that spreads out or propagates throw a medium
Pulse wave
Continuous wave
longitudinal wave
Transversal wave
The displacement is perpendicular to the direction of the propagation of the energy.
Water waves, light ( electromagnetic), earthquakes
Longitudinal wave
Direction od the discplacement of the medium os the same at the direction of the propagation of the energy.