Acceleration
350
1. What is acceleration?
• Our definition: the rate at which velocity
changes.
• A way of describing how fast something
speeds up or slows down
2. What kind of motion does
acceleration refer to?
• Increasing speed
• Decreasing speed
• Changing direction
or any change in velocity (speed and direction)
• How can a car be accelerating if
its speed is constant at 65 km/h?
It can accelerate by changing
direction!
3. How do you calculate
acceleration?
• You must calculate the change in velocity per
unit of time.
• Formula:
4. How is it expressed?
• Usually meters per second per second
• m/s/s or m/s2
5. Example: Calculate the plane’s
acceleration after 5 seconds.
Initial velocity =
Final velocity =
Time =
= 40 m/s – 0 m/s
5s
= 8 m/s2
6. Example: a car slows down from 60 m/s
to 10 m/s in 10 seconds. What is its
acceleration?
a = 10 m/s – 60 m/s
10 s
a = -50 m/s
10s
a = -5 m/s/s or -5 m/s2
ACCELERATION
FORMULA:
7. What is negative acceleration?
• Slowing down or decelerating
8. How can you graph acceleration?
• Speed versus time graph!
• X-axis = time
• Y-axis = speed
Accelerating!
• How would the slope of the graph
change if the cyclist were
accelerating at a greater rate?
The slope would be steeper!
• What about a lesser rate?
The slope would be less steep
9. How can you interpret graphs of
speed versus time?
Speed is increasing
Positive acceleration
Speed
Speed is decreasing
Negative acceleration
Speed
Time (s)
Speed remains the same
Constant speed!
Time (s)
• Or by a distance versus time graph
Xcelerator at Knott’s accelerates the
passengers from 0 m/s to 38 m/s in 2.3
seconds. What is the acceleration?
10. What is the difference between
a linear and nonlinear graph?
• Linear = straight line
• Nonlinear = not a straight line