Theories Flashcards
Newton’s First Law
No net force = no acceleration
Newton’s Third Law
For every reaction, there’s an equal and opposite reaction
Static Force vs. Kinetic Force
Greater than kinetic force because there are more forces acting to keep an object stationary than to move it once its in motion
Uniform Circular Motion
Object moving in a circular path with constant speed
Static Equilibirum
Fnet, τnet, and v=0
Translational Equilibirum
Fnet = 0
Rotational Equilibirum
τnet = 0
Power
The faster work gets done, the greater the power
Kinetic Energy
Is scalar
Changes to Potential Energy
+mgh if height is increased
-mgh if height is decreased
Conservation of Mechanical Energy
KEi + PEi = KEf +PEf
Conservation of Momentum
Δp(system)=0 (pi=pf)
Elastic Collision
p(total) and KE(total) are conserved
Inelastic Collision
p(total) is conserved
Perfectly Inelastic Collision
objects stick together
Energy travels
Positive energy travels into a system, negative energy travels out of a system
First Law of Thermodynamics
ΔE=Q-W (+Q as heat moves into system, +W as work is done by system)
Energy vs. Temperature
Internal energy is proportional to the object’s absolute temperature
Isobaric Process
Constant pressure (W=PΔV)
Isochoric Process
Constant volume (W=0)
Isothermic Process
Constant temperature (decrease P, no change in ΔE)
Adiabatic Process
No heat transfer but energy transfer as work (ΔQ=0)
2nd Law of Thermodynamics
All processes seek to increase disorder/entropy (S)
Archimedes Principle
Magnitude of bouyant force is equal to the weight of the fluid displaced by the object
Floating Object
density (object) < density (fluid) –> weight (object) = F (bouy)
Bernoulli Principle
y1=y2, fast flowing fluids have low pressure ad slow flowing fluids have high pressure
Bernoulli’s Equation
Total energy (density) within all parts of an ideal fluid is the same
Direction of electric field
+ charges move in the direction of the electric field (E) (- moves in opposite direction of E)
Electric potential
+ charges want to move to regions of lower potential
- charges want to move to regions of higher potential
Conductors
Charges rests on the outer surface and the electric field inside is zero
Principle of Superposition
Net electric force on a charge (q) due to a collection of other charges (Q) is equal to the sum of the individual forces that each Q exerts on q
Current flows
In the direction of positive charge
Electrons flow
the opposite direction of the current/positive charge
Resistors in series
Current is the same for resistors in series
Resistors in parallel
Voltage is the same for resistors in parallel
Kirchhoff’s Rules
- Sum of voltage-drops across resistors is equal to the voltage of the battery
- Amount of current entering a parallel combination of resistors is equal to the sum of the currents that pass through individual resistors
Ground
The ground is at potential zero (potential =0)
Total power
Total power supplied by a battery equals the total power dissipated by the resistors
Capacitance does not depend on
voltage or charge
Diaelectric
Always increases the capacitance - if battery remains attached, V is constant; if batter is taken away, Q is constant
Work done by the battery to charge the capacitor =
PE = 1/2QV = 1/2 CV2 = Q2/2C
Direction of magnetic force
right hand rule for positive q (Reverse for negative q)
Magnetic force
F is always perpendicular for both v and B
F never changes the speed of a particle and does NO work on the particle
Magnetic field
Lines point north to south
B created by long, straight current-carrying wire (B=I/r)
B created by a solenoid (B=I(N/L)
Simple harmonic motion
Dynamic condition: restoring force is directly proportional to displacement from equilibrium (x=0) and points towards that equilibrium point
Kinematics condition: frequency and period are independent of the amplitude of oscillations
Wave Equation
- Wave speed (v) depends on wave type and medium - not on frequency
- A single wave passing between media maintains a constant frequency
Doppler Effect
Approaching, higher frequency
Receding, lower frequency
Total Internal Reflection
If Θ1>Θcrit, where sinΘcrit = n2/n1
