Kinematics in One Dimension Velocity and Acceleration Vocabulary

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 (Xo) toward its final position (Xf) • To find displacement Xf – 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 = Xf – X 0 = ΔX tf – t 0 Δt Measurement in m/s

Strategies for Answering Questions 1. 2. 3. 4. Draw/sketch a picture List what you are given Pick an equation 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 = Vf – Vo Δt tf – t 0 • 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 Xo = 0 when t 0 = 0 • X= vt for constant velocity

Constant Accel • a = constant When to = 0 then X = 0 • Vf = V 0 + at

What is the average acceleration from 0 -10 minutes? What is the displacement and average velocity from 15 -30 minutes?

Constant Accel. Equations Variables X x = Vt Vf = V 0 + at x= ½ (Vf + V 0)t x = V 0 t + 1/2 at 2 Vf 2 = V 02 + 2 ax V 0 Vf a t

Acceleration Due to Gravity • Read pages 104 -105 and (8 mins 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. 80 m/s 2 • Object moves in y direction