Physics - Ch 1: Kinematics and Dynamics Flashcards
SI units
Related to metric system
Vectors
Physical quantities with magnitude and direction
Scalar
Quantities without direction
Vector addition
Tip to tip method or break up into components
Vector subtraction
Change direction of subtracted vector and then add
Vector x scale multiplication
Changes magnitude and could change direction
Dot product
Results in scalar - product of magnitudes*cos(angle btwn them)
Cross product
Results in vector - products of magnitudes*sin(angle btwn them) * u – use RHR to determine direction
Displacement
Vector representation of a change in positions, path independent, equivalent to straight line distance between start and stop location
Distance
Scalar quantity that reflects path travelled
Velocity
Vector Representation of the change in displacement with respect to time (SI - m/s)
Average velocity
Total displacement/total time
Average speed
Total distance traveled/total time
Instantaneous velocity
Limit of the change in displacement over time as the change in time approaches zero
Instantaneous speed
Magnitude of the instantaneous velocity vector
Force
Any push or pull that has the potential to result in an acceleration (SI - N=kg*m/s^2)
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
Friction that exists between two objects that are not in motion relative to each other - can take on many values depending on the magnitude of force applied
Kinetic friction
Friction that exists between two objects that are in motion relative to each other - constant value
Coefficient of friction
Coefficient that depends on two materials in contact. Coeff of static friction is always higher than the coeff of kinetic friction - unitless
Mass = weight?
NO
Mass
Measure of the inertia of an object - its amount of material, scalar (SI - kg)
Weight
The force experienced by a given mass due to its gravitational attraction to the Earth, vector (SI- N)
Acceleration
Vector representation of the change in velocity over time (SI- m/s^2)
Newtons first law
aka Law of inertia - an object with remain at rest or move with a constant velocity if there is no net force on the object
Newton’s Second Law
Any acceleration is the result of the sum of the forces acting on the object and its mass
Newton’s Third Law
Any two objects interacting with one another experience equal and opposite forces as a result of their interaction
Linear motion
Motion in which the velocity and acceleration vectors are parallel or antiparallel
Projective motion
Contains both an x and y components. assuming negligible air resistance, the only force acting on the object is gravity
Inclined planes
Type of two-dimensional movement, easiest to analyze dimensions being parallel and perpendicular to surface of the plate
Circular motion
Movement in circular direction, has radial and tangential dimensions
Uniform circular motion
The only force is the centripetal force pointing radially inwards, the instantaneous velocity vector always points tangentially
Free body diagrams
Representations of the forces acting on an object, useful for equilibrium and dynamic problems
Translational equilibrium
Occurs in the absence of any net forces acting on an object, object has 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, constant angular velocity
Torque equation
tau = r x F = rFsin(theta)*u
Centripetal force
Force that points radially inward during circular motion, generates centripetal acceleration
Vector magnitude
Use pythagorean theorem
Magnitude of the gravitational force between two objects
F_g = (Gm1m2)/r^2
Static friction magnitudes
0<= f_s <= mu_s*N
Normal force
Component of the force between two objects in contact that is perpendicular to the plane of contact between the object and the surface upon which it rests
Kinetic friction magnitude
f_k = mu_k*N
Relationship between weight and mass
F_g = m*g
Center of mass/gravity
Where the weight of an object can be though of as being applied at a single point
G (universal gravitational constant)
6.67E-11 N*m^2/kg^2
Center of mass of a uniform object
Geometric center
Deceleration
Acceleration in the direction opposite the initial velicty
Average acceleration
Total change is velocity/total change in time
Instantaneous acceleration
Average acceleration as DELTAT approaches 0
Newtons second law equation
F_net = m*a
Newtons first law equation
F_net = 0 if a=0
Newtons third law equation
F_AB = -F_BA
Kinematic equation v =
v = v_o + at
Kinematic equation x =
x = v_ot + at^2/2
Kinematic equation v^2 =
v^2 = v_o^2 + 2ax
Kinematic equation x =
v_bar*t
Air resistance
Opposes motion of an object, its value increases as the speed of an object increases
Drag force
Force opposing motion of an object, its value increases as the speed of an object increases until the drag force equals F_g
Terminal velocity
Constant velocity where a falling objects force due to gravity equals the drag force
Splitting gravity on inclined plane
F_gll = mgsin(theta) F_gperp = mgcos(theta)
Centripetal force equation
F_c = m*v^2/r
Dynamics
The study of forces and torques
Rotational motion
Forces are applied against an object in such a way as to cause the object to rotate around a fulcrum
Fulcrum
Fixed pivot point for rotational motion
Torque
aka moment of force, application of a force a distance away from a fulcrum
Positive torque direction
Counterclockwise
