Chap 1-3 Acceleration

Chap 1-3 Acceleration

Lesson Objectives "I can..."

• Explain how acceleration relates to motion

• Analyze graphs to see how Speed/ Velocity and Time relates to acceleration

• Analyze Graphs to see how Distance/ TIme relates to acceleration

An object accelerates when its velocity changes as a result of:

• Increasing Speed

• Decreasing Speed

• Change in direction (even if an object is traveling at constant speed)

Multiple Choice

Are the horses in the carousel accelerating even though their speed is constant?

• Yes

• No

• Not sure, need more info

Calculating Acceleration

• Acceleration= (Final Speed- Initial Speed)/ Total TIme

Multiple Select

What is the unit for Acceleration?

• Distance/ time

• Distance/ time²

• m/s

• m/s²

• km/ hr

Multiple Choice

A bicyclist started from rest along a straight path. After 5s, his speed was 8m/s. What was his acceleration during the time?

• 1.6 m/s

• 1.6 m/ s²

• 1.5 m/s²

Speed – Time Graphs

• Shows how  speed changes over time

• X axis = TIME

• Y axis = SPEED

Object at Rest

• The speed is zero and does

   not change

• Horizontal line (like a

  distance – time graph  y = 0

Constant Speed

• The line will be HORIZONTAL

• The further the line is from the X-AXIS the FASTER it is moving.

Speeding Up

• The line on a speed – time graph is CLOSER to the x-axis in the BEGINNING of the time period when it has a LOWER speed

• The line slants  UPWARD toward the right side of the graph as the speed INCREASES     

  
  

Open Ended

What is happening to the speed in this graph?

Slowing Down (Negative Acceleration)

• When initially starting to slow down the  point representing speed is FAR from the x-axis.

• When the line touches the x-axis, the speed is ZERO and the object

  stopped.

• The line on a speed-time graph slopes downward to the right. 

Comparing Distance – Time and

Speed – Time Graphs

• OBJECTS AT REST

• Distance from reference point doesn't change

• Speed is ZERO and doesn't change

Multiple Choice

What are these Graphs showing?

• Increasing Speed

• Constant Speed

• Decreasing Speed

• Object at rest

Constant Speed

• Distance increases at a steady rate

• Object's speed does not change, but it is not zero

Multiple Choice

What are these graphs showing?

• Increasing speed

• Constant Speed

• Object at Rest

• Decreasing Speed

Decreasing Speed

• As the distance increases the rate of increase gets smaller over time

• The speed of the object decreases at a steady rate over time

Multiple Choice

What are these graphs showing?

• Increasing Speed

• Constant Speed

• Decreasing speed

• Object at rest