2. Time passes.
Will you?
1st atomic clock

3. when something occurs (an event)
I. Time t is___________________________________
It is a _____________________________
scalar (no direction)
In physics, the time between two ___________ is
is called the ___________________________ .
events
time interval
event 1
occurs at t =
event 2
occurs at t = ti tf
For example, if…
initial
ti = ____________ time =
5.0 s
tf = ____________ time =
final
8.5 s

4. Then the time interval: tf – ti = Dt equals
Dt = tf – ti =
3.5 s
8.5 s -
5.0 s =
positive
The time interval will always be ______________ .
In Regents Physics, instead of ________ , we use
the symbol _____ for time intervals and often just
call it the ____________ . Remember that _____
represents ____________________________________ .
The basic unit for time is the __________________ .
Other units, such as ___________________________
must usually be converted into _________________
before solving any problems. Dt t
time t
how long a certain process lasts
second, s
minutes, hours, etc
seconds

5. How fast is Usain Bolt?
What is the fastest speed possible?

6. II. speed v = _______________________________
=________________________________
=_________________________________
how fast an object moves
time rate of change in distance
a scalar (no dir., only mag.)
Ex:
v = 55 mph
mag.
Speed v can be ______________ (not changing), or
it can change. If it changes, the speed at any
instant is called the ____________________ speed.
The ______________speed, vavg = v is:
constant
instantaneous
average
Equation for v from PRT
(Physics Reference Tables):

7. Physics Reference Tables, last page:
Further down, find:

8. speed v = ______________________
=____________________________________
=_____________________________________
how fast an object moves
time rate of change in distance
a scalar (no dir., only mag.)
Ex: v = 55 mph
mag.
Speed v can be ______________ (not changing), or
it can change. If it changes, the speed at any
instant is called the ____________________ speed.
The ______________speed, vavg = v is:
constant
instantaneous
average
Equation for v from PRT
(Physics Reference Tables): v
= d/t

9. Ex: Jenny runs 95 meters in 15 seconds.
Find her average speed. Show all work. v
= d/t
= 95 m/15 s
= 6.3 m/s
____________ units are made
up of…..
derived
…the 4 _____________________ (basic) units:
m, A, s, kg
meter, Ampere, second, kilogram
fundamental

10. Ex. A car, initially moving at a speed of 25 m/s,
increases its speed to 45 m/s in 3.0 seconds. What is its average speed during the 3.0 s?
initial
vi = ____________ speed =
25 m/s
vf = ____________ speed =
final
45 m/s
 This equation is NOT
in your PRT. You must
_____________________ .
v = (vi + vf) 2
memorize it
v =
(25 m/s + 45 m/s)
= 35 m/s 2

11. How far will the car in the last example
travel in 12 seconds?
t =
v =
Given:
12 s v
= d/t
35 m/s
35 m/s =
d/12 s
Unknown:
420 m
= d
d =
Word problem hints:
1/ If an object starts from rest: vi =
2/ If an object comes to rest: vf =
3/ If the speed of an object does NOT change,
v =
vi =
vf = v

12. Ex. Units for speed v:
units of ______________
units of speed =
[v] =
Put a rectangle around units of distance,
and an oval around units of speed:
m cm/s km/h mi
1/s ft/s in m/s2
mph km in/y m/s
cm h s km/h
distance
time
[d] / [t]

13. III. velocity v = _________________________________
time rate of change in displacement
displacement =
time
= ________________________________ __________________________________
a vector with the same
dir. as the displacement
Ex:
v = 55 mph, north
dir.
mag. of the velocity = the ____________
speed
velocity = ___________ + ________________
speed
direction
Draw velocity as an _________:
arrow
55 mph

14. Does this show speed or velocity?

15. Note: Speed and velocity have same _________
and use the same_______________:
units
equation
average velocity:
Ex: Godzilla moves 5.0 x 102 meters east in
2.0 seconds. Find his average velocity.
If you assume that east is positive, you may
write this velocity as:

16. Physics Reference Tables, last page:
Further down, find:

17. Note: Speed and velocity have same _________
and use the same_______________:
units
equation
average velocity: v
= d/t
Ex: Godzilla moves 5.0 x 102 meters east in
2.0 seconds. Find his average velocity. v
= d/t
= 5.0 x 102 m, east /
2.0 s
= 250 m/s, east
If you assume that east is positive, you may
write this velocity as: v
= m/s

19. Ex: Mr. Siudy walks 1) 6.0 m east in 4.0 s,
then runs 2) 2.0 m west in 0.50 s. Find his
average speed in each part, and 3) the average
speed over the entire time. 1) v
= d/t
= 6.0 m
4.0 s
= 1.5 m/s
= 2.0 m
0.5 s 2) v
= d/t
= 4.0 m/s
= 8.0 m
4.5 s 3) v
= d/t
= 1.7m/s
d = the _____________ distance
total
Why is the average speed over the entire time
closer to the answer for part _____ ? 1)

20. Now find the average velocities for each part of
the previous example.
d = the __________________ here
displacement 1) v
= d/t
= 6.0 m, E
4.0 s
= 1.5 m/s, E
= m/s 2) v
= d/t
= 2.0 m, W
0.5 s
= 4.0 m/s, W
= m/s 3) v
= d/t
= 4.0 m, E
4.5 s
= 0.89 m/s, E
= m/s
6 m
d = _______________ d:
resultant
2 m
4 m
less
Why is the answer to 3) now ________ than what
it was on the last slide?

21. IV. Uniform motion:
constant ________________
velocity
Uniform
motion
or….
constant ______________
in______________________
speed
1 direction
Ex. A car leaks oil at a constant rate while
moving to the right in uniform motion. Sketch
the pattern of drops it leaves behind.