Physics Flashcards
What are two ways in which you can change acceleration?
Change speed
Change direction
What are the five SUVAT equations?
s = 1/2 * (u+v) * t s = ut + 1/2at^2 s = vt - 1/2at^2 v = u + at v^2 = u^2 + 2as
How do you find displacement from a something-time graph?
Area of a velocity time graph is displacement
Integration is find area / reverse of differentiation - integrate velocity and you get displacement
What is Newton’s First Law or the Law of Inertia?
An object will continue in its state of motion unless compelled to change by a force impressed upon it.
What is Newton’s Second Law?
F = ma
What is Newton’s Third Law?
If object 1 exerts a force on object 2, then object 2 exerts a force back on object 1, equal in strength but in the opposite direction.
What is Newton’s Law of Gravitation?
F = (Gm1m2)/r^2
G = universal gravitational constant (6.67 x 10^-11) m1 = mass of first body m2 = mass of second body r = distance between centre of mass of both bodies
What is static friction and kinetic friction?
Static Friction - the force you initially have to overcome to push something across the floor
Kinetic Friction - the force that slows an object down when it is moving
What is the equation for friction?
Coefficient of Friction * Magnitude of Normal Force
miu*R
What is the general equation to find the gravitational field strength of a specific planet?
g = G * M(planet) / r^2(planet)
What is work done? (equation)
Work Done = Force * Perpendicular Distance
or Work Done = F * d * cos(theta)
How do you work out the work done by a variable force?
eg work done or F(x) = -kx where k is a positive constant?
Work Done is area under line of Force by Distance graph
Work out area under the graph between the two distances
What is the work-energy theorem?
As work done and kinetic energy are both expressed in joules, then
work done = change in kinetic energy
What is an object’s mechanical energy equal to? (equation)
Kinetic Energy + Potential Energy
What is the conservation of mechanical energy?
Initial Mechanical Energy = Final Mechanical Energy
What is the equation for Power?
power = work / time
or power = force * velocity
How do you convert degrees celsius to kelvin?
Celsius + 273 = Kelvin
What equation connects the amount of heat (Q) and the resulting temperature change?
Q = mass * temperature change * c (intrinsic property called the specific heat)
If one material changes the temp of another, then Q1 = -Q2
What equation applies during any phase transition?
Q = mL
where L is the latent heat of transformation
and m is the mass
What are the three principles modes of which energy can be transferred?
Conduction, Convection, and Radiation
Conduction - vibration of particles
Convection - hot air rises and cold air sinks
Radiation - EM waves
When a substance absorbs or gives off heat, what two things can happen?
- Temperature of the substance change
or - Substance can undergo a phase change
What is the equation that links change in length of a material with change in temperature?
Change in Length = Coefficient of Linear Expansion (intrinsic) * Original Length * Change in Temperature
What is the equation that links change in volume of a material with change in temperature?
Change in Volume = Coefficient of Volume Expansion (intrinsic) * Original Volume * Change in Temperature
What is the equation for pressure?
Pressure (Pa) = Force / Area
What is the Ideal Gas Law? (equation)
Pressure * Volume = n (number of moles of gas) * R (8.31) * Temperature
Temperature is in kelvins
What is the average Kinetic energy of an ideal gas?
KE = 3/2 * Temperature (kelvins) * 1.38*10^-23
What is the average velocity of an ideal gas?
Square root of [(3/Molar Mass) * R (8.31) * Temperature (kelvins)]
What is the zeroth law of thermodynamics?
If objects 1 and 2 are each in thermal equilibrium with object 3, then objects 1 and 2 are in thermal equilibrium with each other.
What is the first law of thermodynamics?
Energy (in the form of heat) is neither created nor destroyed in any thermodynamic system
Change in Internal Energy of system = Heat Added to system - Work Done by system
What is the second law of thermodynamics?
The total amount of disorder - the total entropy - of a system plus its surroundings will never decrease.
eg when water freezes, its entropy decreases (as the atoms are in a more fixed / organised state), but it releases heat, which increases the entropy of its surroundings
Another form is, heat flows from an object at higher temperature to an object at lower temperature, never the other way around
What is the equation for work output per cycle?
Work Output per cycle = difference between heat energy drawn in and heat energy discarded
What is the equation for efficiency?
Work Output per Cycle / Heat Energy Drawn In
Equation for momentum
momentum = mass * velocity
Equation for impulse
impulse = force * time
or
impulse = change in momentum
What is the equation for centripetal acceleration?
centripetal acceleration = v^2 / r
v = velocity r = radius
How do you determine the frequency and time period of a pendulum?
f = 1/2pi * (g/L)^0.5
T = 2pi * (L/g)^0.5
What are the equations for torque?
torque = Force * distance * sin theta
torque = lever arm * Force
What is the equation for angular momentum?
Angular momentum = radius * mass * velocity
What is the conservation of angular momentum?
If the torques on a body balance so that the net torque is zero, then the body’s angular momentum can’t change
Angular Momentum = Rotational Inertia * Angular Momentum
Example of this is ice skaters when they go into a ball, they reduce their rotational inertia. So they spin faster (ie their angular momentum increases)
What is the equation for average angular velocity?
Angular Displacement / Change in Time
Change in Angle / Time
What is the equation for average angular acceleration?
Change in average angular velocity / time
What is Kepler’s First Law?
The orbit of each planet is an ellipse and the sun is at one focus
What is Kepler’s Second Law?
An imaginary line from the sun to a moving planet sweeps out equal areas in equal intervals of time
What is Kepler’s Third Law?
The ratio of the square of a planet’s period of revolution to the cube of its average distance from the sun is a constant that is the same for all planets
T^2 / a^3
where a is the length of the semi major axis of a planet’s orbit
What is the equation for a spring’s elastic potential energy?
U = 1/2 kx^2
What equation links time period and frequency?
T = 1/f
How do you determine frequency and time period from the spring constant and mass of the block?
f = 1/2pi * (k/m)^0.5
T = 2pi * (m/k)^0.5
How do you determine the frequency and time period of a pendulum?
f = 1/2pi * (g/L)^0.5
T = 2pi * (L/g)^0.5
What is the equation for the electric force between two particles?
k *|q1 * q2| / r^2
