Lesson 12 – speed-time graphs + terminal velocity

• Natuurkunde / Scheikunde
• Middelbare school
• havo, vwo
• Leerjaar 2

This lesson

• Recap rearranging the formula for acceleration
  
• speed time graph + terminal velocity
  
• Check 4.4 + working independently
  

Learning goals 4.4

• Rearrange the formula for acceleration
  
• Read a speed-time graph correctly
  
• Explain terminal velocity
  

a=​t​​v​f​​−v​i​​​​

vf=(a⋅t)+vi

vi=vf−(a⋅t)

t=​a​​v​f​​−v​i​​​​

Acceleration:

final velocity:

Initial velocity:

Duration of the acceleration: 

• A car accelerates at a rate of 13m/s2 for 6 seconds, it reaches a speed of 128 km/h. Calculate its initial speed.
  

• A rocket launching  accelerates from rest a rate of 1.5 km/s2 for 0.00222222222 Hour (8 seconds). Calculate the speed it reaches.

• A cyclist decelerates from 22 m/s to a speed of 37 m/s at a rate of 7,5 m/s2. Calculate the time this took.
  

Speed-time graphs

The slope of the line shows the velocity of the movement

The slope of the line shows the acceleration of the movement

Speed-time graphs

Positive gradient: acceleration

Flat line: 

constant velocity

Negative gradient:

Deceleration

What does the area under a graph tell you?

What does the area under a graph tell you?

• Area = length x width
  

• Area under speed time graph =  speed x time
  

•  speed x time = distance traveled
  

Calculate the distance traveled in this journey

Terminal velocity

Check worksheet 4.4

• Check your answers with your neighbour using the answer sheet.
  

• Done: Start studying chapter 4
  

Learning goals 4.4

• Rearrange the formula for acceleration
  
• Read a speed-time graph correctly
  
• Explain terminal velocity
  

Homework

Read: textbook 4.5

Do: textbook 4.5 yellow block exercises