Bellringer 8/30 ?

1
Bellringer 8/30 ?

• What is the difference between speed and velocity?

2
Todays Target

• I can use observations and appropriate tools to
  document the position and motion of objects. This
  means I can make observations about how an
  objects motion changes.

3
Acceleration
4
REVIEW

• What is motion?
• How do we know an object is in motion?
• How do we measure motion?
• What is the difference between speed and
  velocity?
• How do we find speed?

5
Acceleration

• Consider this a car is stopped at a red light,
  when the light changes the driver gently steps on
  the accelerator and the car speeds up or
  accelerates
• In everyday language acceleration means the
  process of speeding up

6
Acceleration

• Acceleration is the rate at which velocity
  changes
• Remember that velocity is speed and direction
• Acceleration is
• increasing speed
• decreasing speed
• changing direction

7
Increasing Speed

• Any time the speed of an object increases it
  experiences acceleration
• What are some examples of acceleration?
• A car that moves from a stopped position
• Runners taking off

8
Decreasing Speed

• Decreasing speed is also acceleration
• Called negative acceleration or deceleration
• What are some examples of deceleration?
• A ball rolling to a stop
• A car coming to a red light
• An airplane landing

9
Changing Direction

• Remember that velocity involves both speed and
  DIRECTION, so a change in direction is also
  acceleration
• You may think that a car traveling at constant
  speed does not accelerate, but actually it does
  because it will change directions!

10
Changing Direction

• Examples
• Race car drivers rounding a turn
• Any circular motion
• The seats on a Ferris wheel

11
Did you get it?

• How is it possible for a car to be accelerating
  if its speed is steady at 65 mph?

12
Determining Acceleration
Speed Time
60 km/h 0s
62 km/h 1s
64 km/h 2s
66 km/h 3s
13
Determining Acceleration
Speed Time
12 m/s 0s
8 m/s 1s
4 m/s 2s
0 m/s 3s