Ch 3 Notes
Mr. Russo
Beaumont High School
Objective Ch 3.1-3.3 (Pg32)
We will be able to find the MAGNITUDE of
the RESULTANT when given two or more
vectors
Vector Quantity
Vector Quantity - A quantity that requires both
MAGNITUDE and DIRECTION
Speed vs. Velocity
70mph or
70 mph North
Scalar Quantity
Scalar Quantity – A quantity that is described
by MAGNITUDE ONLY
3 kg of sand
5 Liters of water
75 minutes
Important Point
MAGNITUDE IS JUST A NUMBER!
Example – What is the magnitude of your age?
Vector
Vector – An arrow that is used to represent the
MAGNITUDE and DIRECTION
Length of arrow = Magnitude (Ex: Speed of car)
Where it is pointing = Direction (Ex: Where car is going)
What is the velocity of the plane
with the wind?
80 km/hr (plane)
20 km/hr (wind)
Total = 100 km/hr
What is the velocity of the plane
against the wind?
80 km/hr (plane)
-20 km/hr (wind)
Total = 60 km/hr
Resultant Vector
Resultant Vector – The sum of two or more
vectors
What formula do you use if two
vectors are perpendicular?
Pythagorean Theorem (a2 + b2 = c2)
60km/hr
Head to Tail Method
(Book teaches parallelogram
method)
80km/hr
100km/hr
60km/hr
Components
Components – Any vector can be changed into 2
“pieces” that are perpendicular to each other
Figure 3.6
Is it possible to surf a wave and go
faster than the wave?
Yes
Going
with wave
Riding wave at
an angle
Riding wave at a
larger angle
Objective: Notes 3.4-3.5 (Pg 35)
We will be able to explain how the path of the
projectile can be broken down into its x and y
components.
Projectiles
Projectile – Any object that moves through
space and is only acted on by gravity
Describe the horizontal component
of a projectile?
Just like a ball rolling across a table
Constant velocity (Equal spacing in equal
intervals of time)
No Acceleration
No Horizontal Force
Describe the vertical component of a
projectile?
Just like free fall
There is a force due to gravity
The projectile will accelerate downward
How are the vertical and horizontal
components related?
They are independent of each other.
A projectile moving up and down does not
affect how it moves left or right
What does this mean?
Explain Rifle
Scenario
Explain Monkey and
Hunter Scenario
Show Monkey and
Hunter videos
Penny Activity
What do you notice about the
Horizontal component?
The vertical component is the same because…
There is no force acting horizontally
What do you notice about the
vertical Component?
Vertical component looks just like an object in
free fall
Gravity is the only force vertically
What angle will give a projectile the
most distance?
45 degrees
What is the relationship between 60°
and 30°?
If kicked with the same force, they land in the
same spot
When is the path not a true
parabola?
When we take into account air resistance.
What is the speed of a projectile
when it hits the ground?
The same speed as when it started.
Projectile Motion Example Problems
Harry accidentally falls out of a helicopter that
is traveling 15 m/s. He plunges into a
swimming pool 2 seconds later. Assuming no
air resistance, what was the horizontal distance
between Harry and the swimming pool when he
fell from the helicopter?
Projectile Motion Example Problems
While standing on a 10.0-m-high quarry wall,
Clarence tosses a piece of granite into the water
below. If Clarence throws the rock horizontally
with a velocity of 3.0 m/s, how far out from the
edge of the cliff will it hit the water?
Projectile Motion Example Problems
Joe stands on a jetty hitting golf balls into the
river below. If Joe hits a golf ball with a
horizontal velocity of 45 m/s, and it lands in
the water a horizontal distance of 200 m from
where Joe is standing, what is the height of the
jetty?
Projectile Motion Example Problems
Harry and Angela look from their balcony to a
swimming pool below that is 15m from the
bottom of their building. They estimate the
balcony is 45 meters high. How fast would they
have to jump horizontally to reach the pool?
Projectile Motion Example Problems
A boy on a 20 m high tower throws a ball a
distance of 60m. What speed is the ball thrown?