![Page 1: Acceleration The rate at which velocity changes. Acceleration Acceleration can be described as changes in speed, changes in direction, or changes in both](https://reader036.vdocuments.us/reader036/viewer/2022082820/5697bf901a28abf838c8e0c3/html5/thumbnails/1.jpg)
AccelerationThe rate at which velocity changes
![Page 2: Acceleration The rate at which velocity changes. Acceleration Acceleration can be described as changes in speed, changes in direction, or changes in both](https://reader036.vdocuments.us/reader036/viewer/2022082820/5697bf901a28abf838c8e0c3/html5/thumbnails/2.jpg)
Acceleration• Acceleration can be described as changes in
speed, changes in direction, or changes in both
• Acceleration is a vector• Shows how velocity changes
![Page 3: Acceleration The rate at which velocity changes. Acceleration Acceleration can be described as changes in speed, changes in direction, or changes in both](https://reader036.vdocuments.us/reader036/viewer/2022082820/5697bf901a28abf838c8e0c3/html5/thumbnails/3.jpg)
Acceleration • Acceleration can be caused by an positive
change in speed (increase)• Acceleration can also be caused by a negative
change in speed (decreasing)• Negative acceleration is known as
deceleration
![Page 4: Acceleration The rate at which velocity changes. Acceleration Acceleration can be described as changes in speed, changes in direction, or changes in both](https://reader036.vdocuments.us/reader036/viewer/2022082820/5697bf901a28abf838c8e0c3/html5/thumbnails/4.jpg)
Acceleration example
• You get on a bus and feel the bus “accelerate” as you go down the street. When the bus is keeping a constant speed, its acceleration is zero.
• After a while the bus stops, since the speed is changing the bus is accelerating. (called deceleration)
![Page 5: Acceleration The rate at which velocity changes. Acceleration Acceleration can be described as changes in speed, changes in direction, or changes in both](https://reader036.vdocuments.us/reader036/viewer/2022082820/5697bf901a28abf838c8e0c3/html5/thumbnails/5.jpg)
Free Fall
• The movement of an object toward Earth solely because of gravity
• It is acceleration due to a change in speed
![Page 6: Acceleration The rate at which velocity changes. Acceleration Acceleration can be described as changes in speed, changes in direction, or changes in both](https://reader036.vdocuments.us/reader036/viewer/2022082820/5697bf901a28abf838c8e0c3/html5/thumbnails/6.jpg)
Unit for Acceleration
• Remember the unit for velocity is meters/second
• The unit for acceleration is meters/second2 or m/s2
• Objects falling near Earth’s surface accelerate downward at 9.8 m/s2
• Each second an object is in a free fall, its velocity increases downward by 9.8 meters per second.
![Page 7: Acceleration The rate at which velocity changes. Acceleration Acceleration can be described as changes in speed, changes in direction, or changes in both](https://reader036.vdocuments.us/reader036/viewer/2022082820/5697bf901a28abf838c8e0c3/html5/thumbnails/7.jpg)
Free Fall
• Look at p. 343 and the rock being dropped down the well
• After 1 second the stone will be falling at 9.8 m/s
• After 2 seconds the stone will be falling at 19.6 m/s (2 x 9.8)
• The change in the stones speed (acceleration) is 9.8 m/s2
![Page 8: Acceleration The rate at which velocity changes. Acceleration Acceleration can be described as changes in speed, changes in direction, or changes in both](https://reader036.vdocuments.us/reader036/viewer/2022082820/5697bf901a28abf838c8e0c3/html5/thumbnails/8.jpg)
Changes in Direction• Acceleration is not always due to a change in
speed• You can accelerate even if you are going at a
constant speed• For example, if you are riding a bicycle and go
around a curve, you are accelerating even though you are keeping a constant speed but you are changing direction
• A carousel is traveling at a constant speed but is accelerating since its direction is changing constantly
![Page 9: Acceleration The rate at which velocity changes. Acceleration Acceleration can be described as changes in speed, changes in direction, or changes in both](https://reader036.vdocuments.us/reader036/viewer/2022082820/5697bf901a28abf838c8e0c3/html5/thumbnails/9.jpg)
Constant Acceleration
• The velocity of an object moving in a straight line shows constant acceleration
• This is when there is a steady change in velocity
• The velocity of an object changes by the same amount each second
• A plane’s acceleration may be constant at take-off time
![Page 10: Acceleration The rate at which velocity changes. Acceleration Acceleration can be described as changes in speed, changes in direction, or changes in both](https://reader036.vdocuments.us/reader036/viewer/2022082820/5697bf901a28abf838c8e0c3/html5/thumbnails/10.jpg)
Calculating Acceleration
• You can calculate acceleration for a straight-line motion by dividing the change in velocity over the total time
• a = acceleration, vi = initial velocity and vf = final velocity
• So acceleration = change in velocity/total time
a= (vf – vi)/t
![Page 11: Acceleration The rate at which velocity changes. Acceleration Acceleration can be described as changes in speed, changes in direction, or changes in both](https://reader036.vdocuments.us/reader036/viewer/2022082820/5697bf901a28abf838c8e0c3/html5/thumbnails/11.jpg)
Calculating Acceleration• If velocity increases, then the acceleration is
positive• For example, coasting down a hill on a bicycle
• If velocity decreases, then the acceleration is negative
• For example, coasting on a bike at the bottom of the hill, your velocity will decrease