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Notes: Acceleration
CW: Speed, Velocity and Acceleration
H: Lesson 17 Acceleration
Acceleration
February 16, 2009
Objectives1. Define acceleration and deceleration
2. Describe the relationship between velocity and acceleration
3. Calculate acceleration
Speed – Velocity -
Velocities can be combined.
Rowing downstream at 16 km/h southeast on a river which is moving 10 km/h southeast
results in a total velocity of 26 km/h southeast.
Rockets are launched in the same direction as the earth rotates.
Added boost of 1800 km/h!
Acceleration
the rate of change in velocity
final velocity – initial velocity time
Acceleration
A = Vf – Vi
T
Acceleration equation
A = V T
is
pronounced delta
Acceleration unitskm / h /h or km / h2
m/s/s m / s2
km / h /s
kilometers per hour per hour
meters per second per second
kilometers per hour per second
Example problem
A roller coaster’s speed at the top of a hill is 10 m/s. Two seconds later, it reaches the bottom of the hill with a speed of 26 m/s. What is the acceleration of the roller coaster?
Vi
Vf
t
A = V T
Acceleration equation
A = V T
Final velocity = 26 m/s Initial velocity = 10 m/s Time = 2 s
A = 26 m/s – 10 m/s = 16 m/s = 8 m/s/s
2s 2s
Deceleration
Negative acceleration
Example Problem At the end of a race,
a bicycle is decelerated from a velocity of 12 m/s to a rest position in 30 seconds. What is the deceleration of this bicycle?
Vi
Vf t
Final velocity = 0 m/s
Initial velocity = 12 m/s
Time = 30 s
A = V T
Acceleration equation
A = V T
Final velocity = 0 m/s Initial velocity = 12 m/s Time = 30 s
A = 0 m/s – 12 m/s = -12 m/s = -0.4 m/s/s
30s 30s
If a rocket in space is moving at a constant velocity of 9.8 m/s and then uses its propulsion system to accelerate to 12.0 m/s during a 3.0 minute burn, what would be the acceleration of the rocket?
A = Vf – Vi
t
If a rocket in space is moving at a constant velocity of 9.8 m/s and then uses its propulsion system to accelerate to 12.0 m/s during a 3.0 minute burn, what would be the acceleration of the rocket?
A = Vf – 9.8 m/s
t
If a rocket in space is moving at a constant velocity of 9.8 m/s and then uses its propulsion system to accelerate to 12.0 m/s during a 3.0 minute burn, what would be the acceleration of the rocket?
A = 12.0 m/s – 9.8 m/s
t
If a rocket in space is moving at a constant velocity of 9.8 m/s and then uses its propulsion system to accelerate to 12.0 m/s during a 3.0 minute burn, what would be the acceleration of the rocket?
A = 12.0 m/s – 9.8 m/s
3 min
A = 0.73 m/s/min