21.4 CHAPTER 21. MOTION IN ONE DIMENSION
- Conclusion
- Answer the following questions:
a. How many cars took less than 3 s to travel 50 m?
b. What was the shortest time a car took to travel 50 m?
c. What was the average time taken by the 20 cars?
d. What was the average speed of the 20 cars?
e. Convert the average speed to km·h−^1.
Acceleration ESAGY
DEFINITION: Average acceleration
Average acceleration is the change in average velocity divided by the time
taken.
Quantity: Average acceleration (~aav) Unit name: metre per second
squared Unit symbol: m·s−^2Acceleration is a measure of how fast the velocity of an object changes in time. If we have
a change in velocity (∆~v) over a time interval (∆t), then the average acceleration (~aav) is
defined as:average acceleration (in m·s−^2 )=change in velocity (in m·s− (^1) )
change in time (in s)
~aav=∆∆~vt
We only deal with problems with constant acceleration. This means that the average accel-
eration and the instantaneous acceleration are the same. To make things simpler we will
402 Physics: Mechanics