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Transcript of MOTION!
Speed, Velocity and Acceleration!
What do you already know?
Speed, Velocity and Acceleration:
Describing Speed: Sp=d/t
Who is faster Usain Bolt or a Cheetah
The only difference between Speed
and Velocity is the
new component of
Acceleration : A=v/t
The rate at which the velocity of an object is changing
What do you know about speed?
Describe speed the best you can.
What about Velocity; tell me what you know about velocity.
Finally tell me about Acceleration.
The big questions:
How can I calculate motion?
How do i tell the difference from speed and velocity; and from velocity and acceleration
the distance an object covers in a certain amount of time
the distance an object covers in a given amount of time
.... in a certain direction.
The equation for average speed is:
The equation for Velocity is:
the rate at which velocity changes with time.
The equation for Acceleration is:
Bolt holds the world record in the 100 meter dash.
Bolt runs an average speed of 10.43 meters per second
The Cheetah holds the record for the fasts burst of speed for a mammal.
The cheetah's average speed is 16.39 meters per seconds
Any combinations of units for distance and time can be used to describe speed.
Example: Kilometers per hour , centimeters
per day , meters per second
The metric system unit for speed is m/s.
YAAAYYYY FINN and Jake are Back
Finn and Jake are being chased by a brain crazy zombie.
The zombie is able to run at 5m/s
If the zombie is able to run 5m/s, Finn and Jake must run at least 6 m/s.
How long must it take them to run a distance of 450m to escape the zombie?
To solve the problem:
Write the equation we are going to use.
Next input the numbers we know.
Solve the equation: t= 450m/6m/s
There are two types of speed we can measure
The speed of an object at any instant.
The total distance traveled by an object divided by the
total time it took.
In this class we will use average speed:
Ex: We can see instantaneous speed anytime we are traveling in a car by looking at the speedometer. That is the speed we are moving in a vehicle at a given point in time.
. It has only
magnitude. It can be represented by a single number.
It has both magnitude and direction. It can be represented by a number and an angle on a coordinate plane.
Increasing velocity is represented by a green arrow.
Decreasing velocity is represented by a blue arrow.
X) Two escalators next to each other going up and down. Each has a speed
of 2 km/h.
Because their direction is opposite, they have different Velocities.
1) If an object continues in the same direction, but
speeds up or slows
it’s velocity has changed.
2) If an object continues at the same speed, but
velocity has changed.
Ways to Change Velocity:
I can run as fast as possible for as long as I like.
I will never change speeds, but my velocity always changes. Why?
Because I am running around a track and my direction always changes.
This is a measure of how the velocity of an object changes with respect to time.
Acceleration =change of velocity
The types of of acceleration:
1) speeding up – positive acceleration
2) slowing down – negative acceleration
3) changing direction.
Another way to think about acceleration is:
final speed - initial speed
Practice with Acceleration!
X) Suppose a jet starts at rest at the end of a runway. As it takes off, it reaches a
speed of 80 m/s in 20 s.
(Straight down the runway, its speed and velocity are the same.)
final speed - initial
PUT THEM IN THE EQUATION
Speed, Velocity & Acceleration!
How to describe motion using Speed, Velocity and acceleration.
Vocabulary and Equations
Two examples of how to calculate speed when given the Distance and the time.
TRY TO FIND HOW FAR BOLT COULD RUN IN 60 SECONDS IF HE STAY AT THE SAME SPEED THE ENTIRE TIME.
STEP 1: WRITE THE EQUATION:
STEP TWO: FIND ALL GIVEN VARIABLES:
SP=10.43m/s & t=60s
Step 3: What is the unknown:
STEP 4: PUT VARIABLES INTO EQUATION:
STEP 5: SOLVE EQUATION:
A scalar quantity is a quantity that just gives magnitude or how much of something.
ex: temperature, speed, how much something cost. Austin is 32 miles away.
A vector quantity is a something that not only tells us the how much part, but also tells me in what directions:
ex: velocity, Austin is 32 miles NORTH
What we know:
What we don't know:
Solve the equation
Be prepared at the start of the next class for 5 question!!!!!