Average Speed

1
Average Speed

• total distance
• total elapsed time
• v d/t

2
Average Speed(When only speeds are known)

• If only speeds are known, then the average
  speed is the sum of the speeds divided by the
  total number of values.
• FOR EXAMPLE Find the average speed of 3m/s, 5
  m/s and 8 m/s ?
• Average speed (3 5 8)/3 5.33 m/s

3
Example of Average Speed

• A track star runs the 5k (5 kilometers) race
  in 15 minutes (900 seconds). What is the average
  speed of the runner?
• 
  

4
Example of Average Speed

• A track star runs the 5k (5 kilometers) race
  in 15 minutes (900 seconds). What is the average
  speed of the runner?
• V total distance /total time

5
Example of Average Speed

• A track star runs the 5k (5 kilometers) race
  in 15 minutes (900 seconds). What is the average
  speed of the runner?
• V total distance /total time
• V 5000 m/900 s

6
Example of Average Speed

• A track star runs the 5k (5 kilometers) race
  in 15 minutes (900 seconds). What is the average
  speed of the runner?
• V total distance /total time
• V 5000 m/900 s 5.55 m/s

7
Instantaneous Speed

• very short distance
• very short time
• v Dd
• Dt

8
Example of Instantaneous Speed

• While running a track star covers a distance of
  one meter in 0.24 seconds. What is his
  instantaneous speed ?

9
Example of Instantaneous Speed

• While running a track star covers a distance of
  one meter in 0.24 seconds. What is his
  instantaneous speed ?
• V ?d /?t

10
Example of Instantaneous Speed

• While running a track star covers a distance of
  one meter in 0.24 seconds. What is his
  instantaneous speed ?
• V ?d / ?t V 1 m / 0.24s

11
Example of Instantaneous Speed

• While running a track star covers a distance of
  one meter in 0.24 seconds. What is his
  instantaneous speed ?
• V ?d / ?t V 1 m / 0.24s
• V 4.17 m/s

12
Velocity

• Speed in a particular direction

13
Acceleration

• Change in velocity
• Change in elapsed time
• a Dv
• D t

14
Example of Acceleration

• A sprinter moves from the starting blocks
  traveling from rest to 9 meters per second in 1.5
  seconds. What is the persons acceleration ?

15
Example of Acceleration

• A sprinter moves from the starting blocks
  traveling from rest to 9 meters per second in 1.5
  seconds. What is the persons acceleration ?
• a V final - V initial
• t final - t initial

16
Example of Acceleration

• A sprinter moves from the starting blocks
  traveling from rest to 9 meters per second in 1.5
  seconds. What is the persons acceleration ?
• a V final - V initial 9 m/s 0
• t final - t initial
  1.5 s 0

17
Example of Acceleration

• A sprinter moves from the starting blocks
  traveling from rest to 9 meters per second in 1.5
  seconds. What is the persons acceleration ?
• a V final - V initial 9 m/s 0
  6 m/s2
• t final - t initial
  1.5 s 0