Ch. 1-4 Flashcards
Displacement
△X = Xfinal-Xinitial
Average Speed
path length/elapsed time
Average Velacity
△x/△t
Instantaneous Velocity
lim (x–> 0) △x/△t
Acceleration
△v / △t
Equation for velocity with constant acceleration
v = v initial + at
Equation for △x with constant acceleration
△x = 1/2 (v initial + v) t △x = v initial t + 1/2at^2
Equation for velocity squared with constant acceleration
v^2 = v initial ^2 + 2a△x
Freely Falling Objects
set acceleration = -9.8 m/s^2 (this is the acceleration of gravity)
Components of a Vector
Ax = Acos ⍬ Ay = Asin ⍬
Magnitude and Direction of a Vector
Magnitude = sqrt (Ax^2 + Ay^2) Direction = tan ⍬ = Ay/Ax
Adding Vectors
draw A, then draw B with the tail of B starting at the tip of A; resultant vector R is drawn from the tail of A to the tip of B;
Rx = Ax + Bx Ry = Ay + By
Negative of a Vector
the vector that gives zero when added to the original vector; opposite directions
Subtracting Vectors
simply add the negative of the vector you are trying to subtract
In the x- direction, when ax is constant, what equations describe motion?
Vx = V initialx + a(x)t △x = v initial(x) t + 1/2a(x)t^2 v(x)^2 = v initial(x)^2 + 2a(x) △x
In the y-direction, what equations describe motion?
v(y) = v initial (y) + a(y)t △y = v initial (y) t + 1/2a(y)t^2 v(y)^2 = v initial (y)^2 + 2a(y) △y
relative velocity
let E be an observer (at the origin of a graph) and let two objects that are moving be A and B and introduce vector notation:
vector R (AE) = position of Car A as measured by E
vector R (BE) = position of Car B as measured by E
vector R (AB) = position of Car A as measured by car B
r (AB) = r(AE) - r(BE)
v(AB) = v (AE) - v(BE)
Newton’s First Law
an object moves with a velocity that is constant in magnitude and direction unless a non-zero net force acts on it
Inertia
the tendency of an object to continue in its original state of motion
Mass
a measure of the object’s resistance to changes in its motion
Newton’s Second Law
the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass
Force Vector
F = ma
measured in Newtons (kg x m/ sec^2)
Gravitational Force
Fg = G(m1m2/r^2)
Weight
w = mg
Newton’s Third Law
If object 1 and object 2 interact, the force F(12) exerted by object 1 on object 2 is equal in magnitude but opposite in direction to the force F (21) exerted by object 2 on object 1
Normal Force when Stationary
n = mg
Objects in Equilibrium
summation of Force = 0
Accelerating Objects
use Newton’s second law ( F=ma);
Forces of Friction
static friction = coeff of static f x n
kinetic friction = coeff of kinetic f x n
Movement in X direction when projectile is close to earth
vx = v xi = vcosθ Δx = v xi t = (vcosθ)t
Movement in Y direction when projectile is close to earth
vy = v = vsinθ - gt
Δy=(vsinθ)t - 1/2gt^2
v^2 = (vsinθ)^2 - 2gΔy
