Chapter 2 Uniformly Accelerated Motion Speed Velocity Acceleration

Acceleration What are the units for acceleration?

Uniformly Accelerated Motion Along a Straight Line t In this case… • acceleration is

Problem Solution Guidelines t Draw a sketch – Indicate origin and positive direction t

More Guidelines t t Rewrite the general equations using the known quantities. Look at

Definitions t Instantaneous Velocity – the slope of the displacement versus time graph t

Free Fall t The force of gravity points downward – Acceleration of gravity near

Sample Problem t A ball is thrown vertically upward at 10 m/s. How high

Projectile Problems – Two Dimensional Kinematics t Ignore air resistance. t ax = 0

The motions in the two directions are independent Horizontal Vertical

Real Motion is the Combination of the Two

2 -D Problem Guidelines t Set up two 1 -D solutions Origin x Positive

2 -D Guidelines Cont’d t t t Write general kinematic equations for each direction

Uniformly Accelerated Motion Along a Straight Line

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Chapter 2 Uniformly Accelerated Motion

Speed

Velocity

Acceleration What are the units for acceleration?

Uniformly Accelerated Motion Along a Straight Line t In this case… • acceleration is a constant • and the acceleration vector lies in the line of the displacement vector.

The 5 Equations! (1) (2) (3) (4) (5)

Problem Solution Guidelines t Draw a sketch – Indicate origin and positive direction t List the given quantities using the symbols of the equatio – Is time known or do we need to find it? – What are we to solve for? t Write the general equations of kinematics

More Guidelines t t Rewrite the general equations using the known quantities. Look at the knowns and unknowns and map a strategy of solution. Check your units Make sure you are answering the question.

Problem Solution Time t Fifteen minutes

Definitions t Instantaneous Velocity – the slope of the displacement versus time graph t Instantaneous Acceleration – the slope of the velocity versus time graph

Displacement Slopes A B Time

Teaming Exercise Next Problem solutions

Free Fall t The force of gravity points downward – Acceleration of gravity near the surface of Earth is called g = 9. 8 m/s 2 = 32. 1 ft/s 2 t Air resistance ignored t We have then the conditions of onedimensional kinematics – straight line motion with constant acceleration.

Sample Problem t A ball is thrown vertically upward at 10 m/s. How high will it get, how long will it be in the air, and how fast will it be moving when it hits the ground.

Projectile Problems – Two Dimensional Kinematics t Ignore air resistance. t ax = 0 t ay = g = 9. 81 m/s 2 downward

The motions in the two directions are independent Horizontal Vertical

Real Motion is the Combination of the Two

2 -D Problem Guidelines t Set up two 1 -D solutions Origin x Positive x xi = vxi = ax = 0 Origin y Positive y yi = vyi = ay = g

2 -D Guidelines Cont’d t t t Write general kinematic equations for each direction Rewrite them for the problem at hand Find the condition that couples the motions (usually time)

Uniformly Accelerated Motion Along a Straight Line