- Speed
- Average Speed
- The distance traveled divided by the time of travel
- Average Speed = distance traveled/time of travel
- s = d/t
- 55 mph
- Instantaneous Speed
- How fast you are going at a given instant
- Gives little indication how long it will take to cover a certain distance.
- The rate at which distance is being covered at a given instant in time.
- Velocity
- Involves the direction of motion as well as how fast the object is going (velocity = speed and direction)
- Vector quantity
- Velocity = distance/time (v = d/t)
- 55 mph due east
- A force is required to change the velocity (friction)
- Instantaneous Velocity
- The velocity of an object at a particular instant in time
- Average Velocity
- The velocity of an object over a certain time period
C) Application: Racing Car Tires
- Acceleration
- Vector quantity
- The rate at which velocity changes
- Acceleration = velocity/time (a = v/t)
- Instantaneous acceleration
- The rate at which velocity is changing at a given instant in time.
- Average acceleration
- The change in velocity divided by the time required to produce that change
a = v/t = (v_{f} – v_{i})/t
t = 5 s
v_{1} = 0 m/s v_{2} = 20 m/s
a = v/t = (v_{f} – v_{i})/t
a = (20 m/s – 0 m/s)/5 s
a = 4 m/s^{2}
- Direction of an acceleration
v_{1} v_{2
}
a
v_{1} v_{2
a
Example
The velocity of a car decreases from 30 m/s to
15 m/s in a time of 3 seconds. What is the average acceleration of the car?
v1 = 30 m/s v2 = 15 m/s
a = vf – vi/t = (15 m/s – 30 m/s)/3s = -5m/s2
a m/s2
Graphing Motion
Graph => Provides an overview of what happened.
}