2. Motion
►Motion – an object’s change in position
relative to a reference point
3. Reference Point
►The Earth’s surface is used as a common
reference point
►A moving object can be used as a reference
point as well
4. Speed
►Speed is the distance traveled divided by
the time interval during which the motion
occurred
►Normally, objects do not travel at a constant
speed
►Average Speed - total distance
total time
5. ►Here is a little bug located at 0 cm at 0
seconds.
7. SPEED
►The speed of the bug is just his distance
traveled divided by how long it takes.
►Speed = distance/time
►Speed = 50 cm/10 s = 5 cm/s
8. Question
►I travelled 25 km in 10 minutes. How 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 is the speed of an object in a
particular direction
►Imagine two birds leave the same tree at
the same time. The both fly at 10km/hr for
5 minutes. Why don’t they end up at the
same place?
11.
12. Velocity
►Velocity appears to be very similar to
speed, however, when describing the
velocity of an object you need to provide a
magnitude and a direction
►Magnitude – the speed of the object
►Direction – the direction the object is
moving
16. ►Calculating velocity is a little more
complicated than calculating speed.
►Velocity = change in position/time
► Velocity = (final position – initial position)/time
► Velocity = (80cm – 100cm)/10 seconds
► Velocity = - 2 cm/s
17. ►For objects moving along a straight line
►A positive velocity means moving to the
right. (usually)
►A negative means moving to the left.
(usually)
18. ►A negative velocity does not mean an
object is moving slower than zero cm/s.
►You can’t move slower than standing
still.
►It just means an object is moving in a
certain direction.
19.
20. Resultant Velocity
►An object can have a resultant velocity if it
is experiencing more than one motion.
►For example if a person walks down the
center of a bus while it is in motion there
are two velocities occurring.
1. The movement of the bus
2. The movement of the person inside the bus
23. Acceleration
►Acceleration is the rate at which velocity
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
27. ► Acceleration = (30 m/s – 0 m/s)/10 s
► a = 3 m/s/s
► The car’s velocity is increasing 3 m/s per
second.
► The car is accelerating towards the right.
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?
34.
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.
