dynamics and space acceleration. learning outcomes acceleration of a vehicle between two points...
DESCRIPTION
Lesson 1 Define the term acceleration. Carry out an experiment to determine the acceleration of a trolley.TRANSCRIPT
Dynamics and Space
Acceleration
Learning Outcomes• Acceleration of a vehicle
between two points using appropriate relationships with initial and final velocity and time of change.
• Acceleration from a velocity time graph.
Lesson 1• Define the term acceleration.• Carry out an experiment to
determine the acceleration of a trolley.
Acceleration Intro
• Have you ever heard a phrase used to describe how quick a car is?
• It can do 0 – 60 in 3 seconds.• This is an example of a cars
acceleration
AccelerationName of Car
Time to accelerate from 0-27m/s (s)
Micra 15.2Focus 12.9Corsa 19.9Ka 13.7Smart car 19.6Mondeo 13.0
Questions to consider:
1. Which car takes the shortest time to speed up to 27 m/s?
2. Which car has the fastest acceleration? Why?
3. Which car takes the longest time to speed up to 27 m/s?
4. Which car has the slowest acceleration? Why?
Acceleration• An acceleration is defined as “the
change in velocity per unit time”.
• It is the change in velocity of a body over a certain time period.
Acceleration• Acceleration, (a), can be calculated by
subtracting the initial velocity, (u), from the final velocity (v), of a body over a certain period of time, (t).
a = v – u t• Acceleration has the unit m/s2
• It is a vector quantity.
Experiment to Measure Acceleration
ResultsQuantity Value
t1, time to pass light gate 1 s
t2, time to pass light gate 2 s
t3, time to travel between light gates s
d, card length m
u, initial velocity (d / t1)
m/s
u, final velocity (d / t2)
m/s
a, acceleration(v – u / t3)
m/s2
Lesson 2• Carry out calculations for
acceleration using the equation a = v – u .
t• State that deceleration is a negative
acceleration.• Calculate acceleration from a slope
on a velocity-time graph.
Example 1
a = ?
v = 27 m/su = 0 m/st = 19.9 s
Example 2
a = 20 m/s2
v = 65 m/su = 5 m/st = ?
Example 3
a = 10 m/s2
v = ?u = 10 m/st = 5 s
Deceleration • If a moving body has a ‘negative
acceleration’ then it is decelerating.
• In other words it is slowing down.
Example
a = ?v = 0 m/su = 25 m/st = 5 s
v-t graph example• Using the v-t graph
below for the motion of a car find:
a) The initial accelerationb) The final acceleration
a) a = v – u t= 10-0
4= 2.5 m/s2
b) a = v – u t= 0-10_ (10-8)= - 5 m/s2
[note –ve sign for deceleration]
Velocity-Time Graphs
Questions on displacement and
acceleration
2011
2008
2009
2000, Qu: 21
2003 Qu: 21
2007 Qu: 21
2010 Qu: 21
SummaryAcceleration
You should now be able to do the following:
• Determine the acceleration of a vehicle between two points using a = v-u .
t
• Calculate the acceleration of a body from a slope on a velocity-time graph.