Physics MCAT Flashcards
4 major kinematic equations
Acceleration of centripetal force
a = (v^2)/r
Centripetal force
The force that is responsible for rotational motion. This can be gravity (orbital) or force of tension that the string exerts on the mass (the mass is tied to a string and swung around).
Definition of torque
Rotational force, caused by a force applied to a lever arm at a certain distance from an object capable of rotating.
Formula to calculate torque
t = Fdsin(θ); with θ is the angle btw the lever arm and the force applied.
Definition of Force
An interaction that can cause an object (mass) to accelerate.
F = ma
Unit: N or kg*(m/s^2)
Definition of Work
The transfer of energy that occurs when an object is moved with a certain displacement.
Unit: Joule (J) = N*m
W = F*d
Angle btw applied force and direction of movement
Conservative force
Path-independent; the amount of work done by a conservative force does NOT depend on its path. Care abt displacement only!
Ex: gravitation, spring force, electromagnetic force,…
Non-conservative force
- dissipate energy
- path-dependent
Ex: friction, air resistance, viscosity
PV Work (another equation for work)
Assume constant pressure, Work a gas does against piston to expand its container.
W = External pressure * Change in V
W = P * delta(V)
If pressure changes, Work = area under the curve of graph of pressure (y-axis) and volume (x-axis).
Mechanical advantage
Allows us to deploy less force, but does not do less work!
We apply less force than it would otherwise be necessary to perform a certain amount of work.
Ex: seesaw, inclined plane, pulley, lever
General formula of mechanical advantage
Mechanical advantage for inclined plane
Mechanical advantage = Length of incline / Height of incline
Mechanical advantage > 1. If = 1, no mechanical advantage.
The more angle increases, the more we shorten length of incline. So it decreases overall mechanical advantage
Power
Power = the rate at which work is done; work per unit of time
- More quickly, more powerful
P = W / delta(t)
Unit: watts (W) = J/s
Power of an object maintaining a constant velocity despite a force opposing that motion
Formula of gravitation force and spring force
Kinetic energy
All objects in motion have kinetic E
Formula of Gravitational and Elastic potential energy
Conservation of energy
Conservation of Energy for non-ideal system
When a system loses energy to environment, it’s due to non-conservative forces (friction, air resistance)
Work-Energy theorem
The work performed on or by an object is equal to the change of its kinetic energy.
- In an ideal system, the magnitude of work done by object A on object B equals the magnitude of work done by object B on object A.
What does (+) work mean?
+ Work done on an object by its environment
+ Increase object’s energy
+ Energy put into a system
What does (-) work mean?
- Work done by object on its environment
- Decrease object’s energy
- Energy taken out of a system
Convert Celsius degree to Kelvin
Celsius = ( T + 273) K
O C = 273 K
Relationship btw Celsius and Fahrenheit
oF = (9/5) C + 32
Reduction potential
Tendency to undergo reduction (willingness to gain electrons)
More positive value, greater tendency to gain electron
Cathode and Anode
Red Cat And Ox
Cathode is where REDUCTION takes place
Anode is where OXIDATION takes place
Calculate reduction potential of a cell (Ecell)
Ecell = Ecathode - Eanode
Unit: V
T/F
Reduction potential of galvanic (voltanic) cell is always positive so that its redox rnx is spontaneous.
True
Calculate specific gravity (SG)
SG = Density of objection / Density of fluid
SG > 1 -> Obj sinks
SG = 1 -> Obj in equilibrium with fluid
SG < 1 -> Obj floats
Doppler effect
When a sound source is approaching an observer, the perceived frequency of the sound increases, resulting higher pitch. This is because the sound waves are compressed as the source moves closer, causing the wavelengths to appear shorter.
When a sound source is moving away from an observer, the perceived frequency of the sound decreases, resulting lower pitch.
Define current (I)
Current = the rate of flow of electric charge. Current flows from (+) pt to (-) pt of voltage.
I = q / t
Unit: A = C/s
Define Voltage (V)
Voltage = the electric potential difference btw 2 pts
Ohm’s Law
V = I*R
V: voltage
I: current
R: resistance
Calculate resistance (R)