Ch 3 Notes

Ch 3 NotesMr. 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 or70 mph North

Scalar Quantity

Scalar Quantity – A quantity that is described by MAGNITUDE ONLY

3 kg of sand5 Liters of water75 minutes

Important PointMAGNITUDE IS JUST A NUMBER!

Example – What is the magnitude of your age?

VectorVector – 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)

80km/hr

60km/hr

100km/hr

60km/hr Head to Tail Method

(Book teaches parallelogram method)

ComponentsComponents – 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?

YesGoing with wave

Riding wave at a larger angle

Riding wave at an 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.

ProjectilesProjectile – 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 ScenarioExplain 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 fallGravity 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?


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?


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?


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?


A boy on a 20 m high tower throws a ball a distance of 60m. What speed is the ball thrown?

Ch 3 Notes

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