Motion Review 1-D Formulas: time t ≥ 0 r(t) Position Function: Tells you the location of a moving object Velocity Function: dr v(t) = dt Tells you how fast the object is moving AND Tells you the direction in which the object is moving v(t) Speed Function: Tells you only how fast the object is moving dv d 2 r = 2 Acceleration Function: a(t) = dt dt Tells you how fast the velocity is changing AND Tells you if the velocity is increasing or decreasing Example: Position Function: Velocity Function: Speed Function: Acceleration Function: When t = 1 : r(t) = t 2 − 4t − 3 v(t) = v(t) = a(t) = 2-D Formulas: time t ≥ 0 r (t) = x(t), y(t) Position Function: Tells you the location of a moving object v(t) Velocity Function: Tells you how fast the object is moving AND Tells you the direction in which the object is moving v(t) Speed Function: Tells you only how fast the object is moving Acceleration Function: a(t) Has both magnitude and direction What do they tell you? Example: r (t) = x(t), y(t) = t 2 , 2t Tells you the location of an object moving on the path described by the parametric equations: x(t) = t 2 y(t) = 2t What is the path? Vector-Valued Functions Review Real(scalar)-Valued Functions: f (t) Domain (input) Range (output) Example: f (t) = t 2 f (3) = Plot: r Vector-Valued Functions: (t) = x(t), y(t) Domain (input) Range (output) 2 r (t) = t , 2t Example: r (3) = Plot: Calculus Derivatives Review Real-Valued Functions: df f f (t +t) − f (t) = lim = lim Definition: f ′(t) = t→0 dt t t→0 t What does it mean? Instantaneous rate of change of output f (t) with respect to input t . How do you use it? Find the slope of the line tangent to the curve at the point (t, f (t)) . How do you find it? Use the derivative rules whenever possible Example: f (t) = t 2 f ′(t) = f ′(3) = Vector-Valued Functions: dr r r (t +t) − r (t) r (t) = = lim = lim Definition: ′ dt t→0 t t→0 t What does it mean? Instantaneous rate of change of output r (t) with respect to input t . How do you use it? How do you find it? r (t) = x(t), y(t) ⇒ r ′(t) = x ′(t), y′(t) Example: r (t) = t 2 , 2t r ′(t) = r ′(3) = Integrals Review Real-Valued Functions: Indefinite Integrals: Definite Integrals: ∫ ∫ f (t)dt = F(t) + C b a where F ′(t) = f (t) f (t)dt = F(b) − F(a) How do you find it? Use the antiderivative rules and the Fundamental Theorem of Calculus Example: f (t) = t 2 2 t ∫ dt = ∫ 2 1 t 2 dt = Vector-Valued Functions: Indefinite Integrals: ∫ r (t)dt = ∫ x(t), y(t) dt = ∫ x(t)dt, ∫ y(t)dt Definite Integrals: ∫ b a r (t)dt = ∫ b a x(t), y(t) dt = ∫ b a b x(t)dt , ∫ y(t)dt a How do you find it? Use the antiderivative rules and the Fundamental Theorem of Calculus on the components of the vector. Examples: ∫ t 3 ,t dt = ∫ e2t ,sin t dt = ∫ π 0 4 cos 4t,sin 4t dt Motion in 2-D Formulas: time t ≥ 0 r (t) = x(t), y(t) Position Function: Tells you the location of a moving object Plot as a position vector Tail at (0, 0) Tip traces the curve with parametric equations: x = x(t) y = y(t) Velocity Function: dr v(t) = = dt Tells you how fast the object is moving AND Tells you the direction in which the object is moving Plot at the point corresponding to time t Tail at (x(t), y(t)) Tip points? v(t) = Speed Function: Tells you only how fast the object is moving Length of the velocity vector (speed is a scalar) 2 dv d r a(t) = = 2 = Acceleration Function: dt dt Plot at the point corresponding to time t Tail at (x(t), y(t)) Tip points? Example: r (t) = x(t), y(t) = t 2 , 2t Position function: r (t) = Velocity function: v(t) = Acceleration function: a(t) = Speed function: v(t) = What is the path if t ≥ 0 ? At t=0 r (0) = Position v(0) = Velocity a(0) = Acceleration v(0) = Speed At t =1 r (1) = v(1) = a(1) = v(1) = At t=2 r (2) = v(2) = a(2) = v(2) = Motion in 3-D Formulas: time t ≥ 0 r (t) = x(t), y(t), z(t) Position Function: Tells you the location of a moving object Plot as a position vector Tail at (0, 0, 0) Tip traces the curve with parametric equations: x = x(t) y = y(t) z = z(t) Velocity Function: dr v(t) = = dt Tells you how fast the object is moving AND Tells you the direction in which the object is moving Plot at the point corresponding to time t Tail at (x(t), y(t), z(t)) Tip points tangent to the curve in the direction of the motion v(t) = Speed Function: Tells you only how fast the object is moving Length of the velocity vector (speed is a scalar) 2 dv d r a(t) = = 2 = Acceleration Function: dt dt Tail at (x(t), y(t), z(t)) Example: r (t) = x(t), y(t), z(t) = 2 sin t, 2 cost, 2t Position function: r (t) = Velocity function: v(t) = Acceleration function: a(t) = v(t) = Speed function: What is the path? At t = 0 r (0) = v(0) = a(0) = v(0) = At t = 1 r (1) ≈ 1.7,1.1, 2 v(1) ≈ 1.1, −1.7, 2 a(1) ≈ −1.7, −1.1, 0 v(1) ≈ 2.8 At t = 2 r (2) ≈ 1.8, −.8, 4 v(2) ≈ −.8, −1.8, 2 a(2) ≈ −1.8,.8, 0 v(2) ≈ 2.8 More 2-D: r (t) = x(t), y(t) = sin(2t), cos(2t) Position function: r (t) = Velocity function: v(t) = Acceleration function: a(t) = v(t) = Speed function: What is the path? At t = 0 r (0) = v(0) = a(0) = v(0) = At t = 1 r (1) ≈ .9, −.4 v(1) ≈ −.8, −1.8 a(1) ≈ −3.6,1.7 v(1) = 2 At t = 2 r (2) ≈ −.8, −.7 v(2) ≈ −1.3,1.5 a(2) ≈ 3.0, 2.6 v(2) = 2 Example: r (t) = x(t), y(t) = sin(t 2 ), cos(t 2 ) Position function: r (t) = Velocity function: v(t) = Acceleration function: a(t) = v(t) = Speed function: What is the path? At t = 0 r (0) = v(0) = a(0) = v(0) = At t = 1 r (1) ≈ .8,.5 v(1) ≈ 1.1, −1.7 a(1) ≈ −2.3, −3.8 v(1) = 2 At t = 2 r (2) ≈ −.8, −.7 v(2) ≈ −2.6, 3.0 a(2) ≈ 10.8,12.0 v(2) = 4 Example: r (t) = x(t), y(t) = 2t − 2 sin t, 2 − 2 cost Position function: r (t) = Velocity function: v(t) = Acceleration function: a(t) = v(t) = Speed function: What is the path? At t = 0 r (0) = v(0) = a(0) = v(0) = At t = 1 r (1) ≈ .3,.9 v(1) ≈ .9,1.7 a(1) ≈ 1.7,1.1 v(1) ≈ 1.9 At t = 2 r (2) ≈ 2.2, 2.8 v(2) ≈ 2.8,1.8 a(2) ≈ 1.8, −.8 v(2) ≈ 3.4