Kinematics in One Dimension Velocity and Acceleration

Vocabulary Mechanics- Branch of physics that focuses on motion of objects and the forces that cause the motion to change. Kinematics- deals with the concepts needed to describe motion without any reference to forces. Dynamics- deals with the effect that forces have on motion.

Displacement A vector that points from an objects initial position (X o ) toward its final position (X f ) To find displacement X f – X 0 = ΔX

Speed Speed- The measure of how fast something is moving Average Speed = Distance Elapsed Time *Note* That speed is a scalar quantity

Velocity Deals with how fast an object moves and its direction Average Velocity = Displacement Elapsed Time V = X f – X 0 = ΔX t f – t 0 Δt Instantaneous Velocity = V= lim Δt 0 ΔX Δt Measurement in m/s

Strategies for Answering Questions 1.Draw/sketch a picture 2.List what you are given 3.Pick an equation 4.Solve the equation for the missing variable 5.Insert numbers into equation

Acceleration Deals with an objects changing velocity Average acceleration= change in velocity change in time a= ΔV = V f – V o Δt t f – t 0 Instantaneous Accel = a = lim Δt 0 ΔV Δt Units of measurement are m/s 2

If Velocity and Accel have… Same signs – object is speeding up Opposite signs- object is slowing down

Constant Velocity If V = constant the a = 0 (no acceleration) Set X o = 0 when t 0 = 0 X= vt for constant velocity

Constant Accel a = constant When t o = 0 then X = 0 and V f = V 0 V f = V 0 + at

What is the average acceleration from 0-10 minutes? What is the displacement and average velocity from minutes?

Constant Accel. Equations EquationsVariables x = Vt V f = V 0 + at x= ½ (V f + V 0 )t x = V 0 t + 1/2at 2 V f 2 = V ax XV0V0 VfVf at

Acceleration Due to Gravity Read pages and (8mins to read / take notes on important info from text about gravity. Object is in free fall Assume no air resistance a = g = 9.80 m/s 2 Downward direction so –g = -9.80m/s 2 Object moves in y direction