Section 1.3 Outline

Acceleration measures how fast velocity changes

I. Speed and direction can change with time

1) acceleration: the rate at which velocity changes with time

2) if velocity does NOT change, there is NO acceleration

3) direction of acceleration determines how an object’s motion changes

3) direction of acceleration determines how an object’s motion changes

a) acceleration in same direction as motion = increase in speed

b) acceleration in opposite direction of motion = decrease in speed

c) acceleration at a right angle to motion = change in direction AND no change in speed

II. Acceleration can be calculated from velocity and time

1) to measure acceleration you need to know how velocity changes with time

a) change in velocity found by subtracting the final and initial velocities

b) time interval can be measured as the velocity changes

2) acceleration measures the change in velocity, not velocity itself

A. Calculating Acceleration

1) Acceleration = final velocity – initial velocity time

A = VFinal- VInitial

T2) Velocity is expressed in units of meters per

second (m/s)3) Acceleration is expressed in units of meters

per second per second (m/s2)4) A negative sign indicates a negative

acceleration meaning a decrease in velocity

C. Velocity – Time Graphs

1) Rising line indicates positive acceleration or an increase in velocity

2) Flat line indicates no acceleration or constant velocity

3) Falling line indicates negative acceleration or a decrease in velocity