1. What is Velocity (Speed)?
• Velocity (speed) – the rate of change of distance
per unit of time.
Speed =
d2 – d1
t2 – t 1
Velocity =
d2 – d1
t2 – t 1

2. What is Acceleration?
• If velocity is the rate of change of distance per
unit of time, then acceleration is …
• … the rate of change of velocity per unit time.

3. What is Acceleration?
• Positive acceleration = speeding up
• Negative acceleration = slowing down
(decelerate)

4. Calculating Acceleration
Velocity =
d2 – d1
t2 – t 1
Acceleration=
v2 – v1
t2 – t1
• So, to determine acceleration, you must know the
beginning velocity, the final velocity, the
beginning time, and the final time.
• Again, this is just like slope on a graph!

5. Calculating Acceleration

6. Calculating Acceleration
• What is the acceleration car that goes from 0 ft/s
to 200 ft/sec in 5 seconds?
• Beginning velocity (v1) = 0 ft/s, final velocity (v2)
= 200 ft/s, beginning time (t1) = 0 seconds, and
final time (t2) = 5 seconds, so

7. Calculating Acceleration
Acceleration =
v2 – v1
t2 – t 1
200 ft/s – 0 ft/s
Acceleration =
5s–0s
• Which equals 200 ft/s ÷ 5 s, or
• 40 ft/s2 (or 40 feet per second per second)

8. Calculating Acceleration
• What is the acceleration roller coaster that
goes from 5 m/sec to 0 m/sec in 10 seconds?
• v1 = 5 m/sec, v2 = 0 m/sec, t1 = 0 seconds, and t2
=10 seconds, so

9. Calculating Acceleration
Acceleration =
Acceleration =
v2 – v1
t2 – t 1
0 m/s – 5 m/s
10 s – 0 s
• Which equals: – 0.5 m/s2
• Acceleration is negative, so roller coaster is
slowing down.

10. Calculating Acceleration

11. Calculating Acceleration
• What is the acceleration of a jet fighter that goes
from 0 mph to 165 mph in 2 seconds?
• v1 = 0 miles/hr, v2 = 165 miles/hr, t1 = 0 seconds,
and t2 = 2 seconds

12. Calculating Acceleration
• First, you must make the time units all the same.
• Initial Velocity = 0 miles/hour = 0 miles/second
• Now, convert 165 miles/hr to miles/sec

13. Calculating Speed and Velocity
165 miles
hr
x
1 hr
3,600 sec
• Now, calculate acceleration
=
0.046 miles
sec

14. Calculating Acceleration
0.046 miles/s – 0 miles/s
Acceleration =
2s–0s
• Which equals 0.023 miles/s2 , or
• 121 ft/s2 (or almost 4 g’s)

15. Brain Pop Clip
• BrainPOP on Acceleration