Physics & math Flashcards
Distance
Scalar quantity that reflects the path traveled.
Displacement
Vector representation of a change in position. It is path independent and is equivalent to the straight line distance between the start and end locations.
Velocity
Vector representation of the change in displacement with respect to time.
Dot Product
[a][b]cos(theta)
Multiplying two vectors using the dot product results in a scalar quantity.
Cross Product
[a][b]sin(theta)
Multiplying two vectors using the cross product results in a vector quantity. The RHR is used to determine the resultant vector’s direction.
Vector
Physical quantity with both magnitude and direction. (e.g. displacement, velocity, acceleration, and force)
Scalar
Quantity without direction. (e.g. speed, coefficient of friction)
SI units
meter, kilogram, second, ampere, mole, kelvin, candela
Force
Push or pull that has the potential to result in an acceleration.
Gravity
Attractive force between two objects as a result of their masses.
Friction
Force that opposes motion as a function of electrostatic interactions at the surfaces of two objects.
Static friction
Exists between two objects that are not in motion relative to each other.
0 <= fs =< mu(s)N
mu(s) = coefficient of static friction
mu(s) > mu(k) always b/c harder to get an object to start moving vs. keeping it moving.
Kinetic friction
Exists between two objects that are in motion relative to each other.
fk = mu(k)N
Whereas static friction can take on many values,
kinetic friction is constant given a constant normal force and coefficient of kinetic friction.
Mass
Measure of the inertia of an object - its amount of material.
Constant regardless of location (e.g. mass on Earth = mass on moon)
Weight
Force experienced by a given mass due to its gravitational attraction to Earth.
Weight = mg
Acceleration
Vector representation of the change in velocity over time.
Newton’s first law / Law of inertia
An object will remain at rest or move with a constant velocity if there is no net force on the object.
F = ma = 0
Newton’s second law
Any acceleration is the result of the sum of the forces acting on the object and its mass.
F = ma
Newton’s third law
Any two objects interacting with one another experience equal and opposite forces a result of their interaction.
“Every reaction has an opposite and equal reaction.”
Fab = -Fba
Linear Motion
Motion with constant acceleration. Includes free fall and motion in which the velocity and acceleration vectors are parallel or antiparallel.
Projectile Motion
Contains both an x- and y- component. Assuming negligible air resistance, the only force acting on the object is gravity.
Separate into x and y components.
Parallel gravity = mgcos(theta)
Perpendicular gravity / Normal force = mgsin(theta)
Inclined planes
2D movement; easiest to consider the dimensions as being parallel and perpendicular to the surface of the plane.
Normal force is perpendicular to the object.
Weight faces straight down the plane.
Circular motion
Has radial and tangential dimensions. In uniform circular motion, the only force is the centripetal force, pointing radially inward. The instantaneous velocity vector always points tangentially.
The centripetal force exerts centripetal acceleration on the object, keeping it from going tangential to the circle (where its velocity vector points.)
Centripetal force = mv^2/r
Free body diagrams
Representations of the forces acting on an object. Useful for equilibrium and dynamics problems.
Translational equilibrium
Occurs in the absence of any net forces acting on an object. An object in translational equilibrium has a constant velocity and may or may not also be in rotational equilibrium.
Rotational equilibrium
Occurs in the absence of any net torques acting on an object. Rotational motion may consider any pivot point, but the center of mass is most common. An object in rotational equilibrium has contstant angular velocity; on the MCAt, the angular velocity is usually 0.
