Acceleration

Mr. Monroe

October 30, 2007

Acceleration ~ is the change in rate of volocity.

Acceleration ~ is the change in rate of volocity.

change in velocity

Acceleration = ----------------------------------------

time taken to change

Acceleration ~ is the change in rate of volocity.

change in velocity

Acceleration = ----------------------------------------

time taken to change

(Vf - Vi)

Acceleration = ----------------------------------------

t

Example with POSITIVE acceleration

Positive acceleration

Initial velocity = 0 km/hr

Final velocity = 80 km/hr

Time = 15 seconds

Example with POSITIVE acceleration

Positive acceleration

Initial velocity = 0 km/hr

Final velocity = 80 km/hr

Time = 15 seconds

(80 km/hr - 0 km/hr)

Acceleration = ----------------------------

15 seconds

Example with POSITIVE acceleration

Positive acceleration

Initial velocity = 0 km/hr

Final velocity = 80 km/hr

Time = 15 seconds

(80 km/hr - 0 km/hr)

Acceleration = ----------------------------

15 seconds

Acceleration = 5.33 km/hr/sec

Example with NEGATIVE acceleration

Negative acceleration

Initial velocity = 80 km/hr

Final velocity = 0 km/hr

Time = 15 seconds

(0 km/hr - 80 km/hr)

Acceleration = ----------------------------

15 seconds

Acceleration = -5.33 km/hr/sec

A plane hits a mountain at a speed of 400 meters per second, and it takes the plane 3 seconds to stop. What is the acceleration of the plane?

A plane hits a mountain at a speed of 400 meters per second, and it takes the plane 3 seconds to stop. What is the acceleration of the plane?

Vf = 0 m/sVi = 400 m/sT = 3 s

(0 m/s) – (400 m/s)------------------------ = - 133 m/s/s (Note that this is negative, hence the sign)

3 s

A car hits a tree going 60 miles per hour. It takes the occupant .1 seconds to stop. What is her acceleration?

A car hits a tree going 60 miles per hour. It takes the occupant .1 seconds to stop. What is her acceleration?

Vf = 0 miles/hourVi = 60 miles/hourT = .1 s

(0 miles/hour) – (60 miles/hour)----------------------------------------- = - 600 miles/hour/second (Note that this is negative) .1 s

This is probably not a survivable accident.

A car hits a tree going 60 miles per hour. It takes the occupant .5 seconds to stop, because she was wearing a seat belt. What is her acceleration?

A car hits a tree going 60 miles per hour. It takes the occupant .5 seconds to stop, because she was wearing a seat belt. What is her acceleration?

Vf = 0 miles/hourVi = 60 miles/hourT = .5 s

(0 miles/hour) – (60 miles/hour)---------------------------------------- = - 120 miles/hour/second .5 s

This is a very survivable accident.

End of first part of presentation.

A cross-country runner accelerates at a rate of 1 meter per second, per second. How fast will he be running in 5 minutes?

A cross-country runner accelerates at a rate of 1 meter per second, per second. How fast will he be running in 5 minutes? The cross-country runner must be Chuck Norris

1 m /s 5 minutes 60 seconds------- x -------------- x ------------------ = 300 m/s s 1 1 minute

Most airplanes could not go this fast

Brett’s car accelerates from 0 meters per second, to 5 meters per second in 2.3 seconds. What is its rate of acceleration? At that rate of acceleration, how fast will it be going in 6 hours?

Brett’s car accelerates from 0 meters per second, to 5 meters per second in 2.3 seconds. What is its rate of acceleration? At that rate, how fast will it be going in 6 hours?

Vf = 5 m/sVi = 0 m/sT = 2.3 s

(5 m/s) – (0 m/s)------------------------ = 2.2 m/s/s is the rate of acceleration 2.3 s

At that rate, how fast will it be going in 6 hours?

2.2 m/s 6 hours 60 min 60 seconds------------ x--------------- x -------------- x -------------- = 47,520 meters per second s 1 1 hour 1 min

At that speed, you would be getting around the world, at the equator, in about 14 minutes.