The document discusses the concepts of motion, speed, velocity, and acceleration, explaining their definitions and relationships. It highlights how speed is defined as distance traveled over time, while velocity includes direction, and details various scenarios for calculating both. The document also addresses acceleration as the rate of change of velocity and provides examples of calculating speed, velocity, and acceleration in different contexts.

1. Motion, Speed, Velocity
Motion, Speed, Velocity
and Acceleration
and Acceleration

2. Motion
Motion
►Motion
Motion – an object’s change in position
– an object’s change in position
relative to a reference point
relative to a reference point

3. Reference Point
Reference Point
►The Earth’s surface is used as a common
The Earth’s surface is used as a common
reference point
reference point
►A moving object can be used as a
A moving object can be used as a
reference point as well
reference point as well

4. Speed
Speed
►Speed
Speed is the distance traveled divided by
is the distance traveled divided by
the time interval during which the motion
the time interval during which the motion
occurred
occurred
►Normally, objects do not travel at a
Normally, objects do not travel at a
constant speed
constant speed
►Average Speed -
Average Speed - total distance
total distance
total time
total time

5. ►Here is a little bug located at 0 cm at
Here is a little bug located at 0 cm at
0 seconds.
0 seconds.

6. ►10 seconds later he is at 50 cm.
10 seconds later he is at 50 cm.

7. SPEED
SPEED
►The speed of the bug is just his distance
The speed of the bug is just his distance
traveled divided by how long it takes.
traveled divided by how long it takes.
►Speed = distance/time
Speed = distance/time
►Speed = 50 cm/10 s = 5 cm/s
Speed = 50 cm/10 s = 5 cm/s

8. Question
Question
►I travelled 25 km in 10 minutes. How
I travelled 25 km in 10 minutes. How
many meters have I travelled?
many meters have I travelled?
25 km * 1000m/km = 25000 m

9. Problem Solving: Calculating
Speed
What is the speed of a sailboat that is
traveling 120 meters in 60 seconds?
What is the speed of a car that is traveling
150 miles in 3 hours?

10. Velocity
Velocity
►Velocity
Velocity is the speed of an object in a
is the speed of an object in a
particular direction
particular direction
►Imagine two birds leave the same tree at
Imagine two birds leave the same tree at
the same time. The both fly at 10km/hr
the same time. The both fly at 10km/hr
for 5 minutes. Why don’t they end up at
for 5 minutes. Why don’t they end up at
the same place?
the same place?

12. Velocity
Velocity
►Velocity
Velocity appears to be very similar to
appears to be very similar to
speed, however, when describing the
speed, however, when describing the
velocity of an object you need to provide
velocity of an object you need to provide
a magnitude and a direction
a magnitude and a direction
►Magnitude
Magnitude – the speed of the object
– the speed of the object
►Direction
Direction – the direction the object is
– the direction the object is
moving
moving

13. Velocity
Velocity
►Ex) A bus has a velocity of 35miles/hr
Ex) A bus has a velocity of 35miles/hr
heading west
heading west

14. ►Suppose our bug starts off at 100 cm.
Suppose our bug starts off at 100 cm.

15. ►And ends up at 80 cm 10 seconds
And ends up at 80 cm 10 seconds
later.
later.

16. ►Calculating velocity is a little more
Calculating velocity is a little more
complicated than calculating speed.
complicated than calculating speed.
►Velocity = change in position/time
Velocity = change in position/time
► Velocity = (final position – initial position)/time
Velocity = (final position – initial position)/time
► Velocity = (80cm – 100cm)/10 seconds
Velocity = (80cm – 100cm)/10 seconds
► Velocity = - 2 cm/s
Velocity = - 2 cm/s

17. ►For objects moving along a straight
For objects moving along a straight
line
line
►A positive velocity means moving to
A positive velocity means moving to
the right. (usually)
the right. (usually)
►A negative means moving to the left.
A negative means moving to the left.
(usually)
(usually)

18. ►A negative velocity does not mean an
A negative velocity does not mean an
object is moving slower than zero
object is moving slower than zero
cm/s.
cm/s.
►You can’t move slower than standing
You can’t move slower than standing
still.
still.
►It just means an object is moving in a
It just means an object is moving in a
certain direction.
certain direction.

20. Resultant Velocity
Resultant Velocity
►An object can have a resultant velocity if it
An object can have a resultant velocity if it
is experiencing more than one motion.
is experiencing more than one motion.
►For example if a person walks down the
For example if a person walks down the
center of a bus while it is in motion there
center of a bus while it is in motion there
are two velocities occurring.
are two velocities occurring.
 1. The movement of the bus
1. The movement of the bus
 2. The movement of the person inside the
2. The movement of the person inside the
bus
bus

21. Example
Example
15 m/s + 1 m/s = 14 m/s

22. Example
Example
15 m/s + =
1 m/s 16 m/s

23. Acceleration
Acceleration
►Acceleration
Acceleration is the rate at which velocity
is the rate at which velocity
changes over time
changes over time
When an object is increasing in velocity over time
it is said to be accelerating.
(positive acceleration)
When an object is decreasing in velocity over time
it is said to be decelerating.
(negative acceleration)
If an object is moving at constant velocity it is said
to be moving with zero acceleration

24. Three Ways to “Accelerate”
►Speed Up
►Slow Down
►Change Direction

25. Acceleration
Acceleration
►Average acceleration =
final velocity – initial velocity
time it takes to change
velocity

27. ► Acceleration = (30 m/s – 0 m/s)/10 s
Acceleration = (30 m/s – 0 m/s)/10 s
► a = 3 m/s/s
a = 3 m/s/s
► The car’s velocity is increasing 3 m/s per
The car’s velocity is increasing 3 m/s per
second.
second.
► The car is accelerating towards the right.
The car is accelerating towards the right.

29. ► a = (0m/s – 20 m/s)/10 s
a = (0m/s – 20 m/s)/10 s
► a = - 2 m/s/s
a = - 2 m/s/s

30. As a roller-coaster car starts down a slope, its
speed is 4 m/s. But 3 seconds later, at the
bottom, its speed is 22 m/s. What is its average
acceleration?
Calculating Acceleration
What information have you
been given?
Initial speed = 4 m/s
Final Speed = 22 m/s
Time = 3 s

31. A satellite’s original velocity is 10,000 m/s.
After 60 seconds it s going 5,000 m/s.
What is the acceleration?
If a speeding train hits the brakes
and it takes the train 39 seconds to
go from 54.8 m/s to 12 m/s what is
the acceleration?

32. Johny completes the bicycle ride with
the final velocity of 10 ms-1
and
acceleration 2 ms-2
within 3s.
Calculate the initial velocity.
You are driving on a highway that
has stop-and-go traffic for miles. It
finally clears up at a point when you
were going at a speed of 2m/s. how
fast will you be going after 9
seconds of constant acceleration at
3m/s^2?

33. A racehorse coming out of the gate
accelerates from rest to a velocity of
15.0 m/s due west in 1.80 s. What is its
average acceleration?

35. A car starts out moving
at 10 m/s10 m/s and accelerates to a
velocity of 24 m/s24 m/s. What
displacement does the car cover
during this velocity change if it occurs
over 10 s?
Distance is the length of the path taken by
an object whereas displacement is the
simply the distance between where the
object started and where it ended up.

36. A rocket is cruising through space
with a velocity of 50 m/s and burns
some fuel to create a constant
acceleration of 10 m/s2. How far will
it have traveled after 5 s?
Later in its journey, the rocket is moving
along at 20 m/s20 m/s when it has to fire
its thrusters again. This time it covers a
distance of 500 m500 m in 10 s10 s. What
was the rocket’s acceleration during this
thruster burn?

37. A car exiting the highway begins with a
speed of 25 m/s and travels down
a 100 m long exit ramp with a
deceleration (negative acceleration)
of 3 m/s2. What is the car’s velocity at
the end of the exit ramp?
A feather is dropped on the moon from a
height of 1.40 meters. The acceleration of
gravity on the moon is 1.67 m/s2
.
Determine the time for the feather to fall
to the surface of the moon.

38. A stone is dropped into a deep well and
is heard to hit the water 3.41 s after
being dropped. Determine the depth of
the well.