Journal Entry: All Motion Is Relative

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Journal Entry: All Motion Is RelativeDirections: Create and complete the following table in your science journal:

ENGAGE Introduction to Motion

Object Is it in motion? Why/ Why not? EXPLAIN!!!

YOU (yes or no)Explain your thoughts in two or three sentences. Your explanation may take a couple of lines, so leave plenty of space.

Hand Sanitizer

Palm Frond

Air

The Sun



Mission Objectives• Know how to accurately describe the position and/or

motion of an object.• Explain what is meant when we say an object is in

motion.• Explain the difference between a scalar and a vector.• Recognize and explain the difference between

distance and displacement.• Use position, speed, direction of motion, and a

reference point to describe the motion of an object.

GOALS Understanding Motion



So what IS motion anyway?!?!• In science, motion is the change of position of an

object relative to a reference point.

• A reference point is an object that appears to stay in place.

• ANY object can be in motion or NOT in motion, depending on the reference point (perspective of the observer).

Introduction Understanding Motion



Describing the Position of an Object• To accurately describe the position of an object, you

must…1. Establish a reference point. You usually need three (3) reference points to locate an object in 3 dimensional space!

2. Measure or estimate the distance of the object from the reference point.

3. Describe the direction of the object’s location relative to the reference point.

• Example: The moose is 0 cm above the goggles cabinet, 6 cm east of the west wall, and 30 cm south of the north wall.

Input Understanding Motion



• When you describe the motion of an object, you should…

1. Establish a reference point.2. Describe how the object’s distance is changing

relative to the reference point (may include speed).

3. Describe the direction the object is moving in relative to the reference point.

Input Understanding Motion

Describing the MOTION of an Object



Journal Entry: Understanding Motion

Write a paragraph that explains how you know when an object is in motion. You may draw diagrams to help make your explanation clear.

Write your explanation in your science journal.

RECALL Understanding Motion



Understanding Motion: Practice

1. Fill in the Blank: A change in position with respect to a reference point is called _____________.

2. Describe the position of the digital clock on the classroom wall.

3. True/False: When standing still in a moving elevator, you are not moving from the reference point of the elevator.If it is false, change the underlined word to make it true!Explain your answer!!!

4. Describe the motion of a baseball that has just been pitched as seen from the reference point of home plate.



Describing Motion• Scalar: A measurement that involves a magnitude.

(Magnitude is an amount or quantity PLUS a unit!)

• Examples: 20 birds, 40 grams, 65 mph, 6 meters.

• Vector: A measurement that involves both a magnitude and a direction or position.

• Examples: 65 mph NE; backing up 5 feet; 7,600 feet above mean sea level.



Distance Versus DisplacementDISTANCE

•Scalar•Direction does NOT matter.•The actual path matters!•The total distance traveled.

•In the Daytona 500, the cars travel a distance of 500 miles.

DISPLACEMENT•Vector•Direction DOES matter!•The path does NOT matter!•The straight-line distance (and direction) the object has travelled from its starting point.

•In the Daytona 500, the cars experience zero displacement (they start where they end).



Journal Entry: Reviewing Relative Motion

Respond to the following question in your sciencejournal:

You are sitting still in your seat on a bus that istraveling 100 km/h on a highway. Is your body at restor in motion? Explain your answer! Use a diagram ifit will help make your answer clear.

REVIEW



SPEED

• Speed is the distance traveled divided by the time taken to travel that distance. It is a scalar quantity!

• Speed is important in describing motion because it tells how fast an object is moving.

• The units for speed are often m/s, but can be any distance unit divided by a time unit.

INPUT Describing Motion



GuidedPractice

Describing Motion



Speed and Velocity: The same… but different!• Direction of Motion Speed and direction of motion

are combined when describing an object’s velocity.

• Velocity is a quantity that tells both how fast an object is moving (its speed) and its direction of motion relative to a reference point.

• Velocity is a vector quantity!

• An object’s velocity may change even if its speed remains constant (by changing direction).




Draw a Venn Diagram comparing and contrasting Speed and Velocity

Speed Velocity

CheckUnderstanding

Describing Motion



• Sometimes the velocity of an object changes. The change in velocity over time is called acceleration.

• Acceleration can be a change in speed, a change in direction, or both.

• The most common units of acceleration are meters per second per second, which can be abbreviated m/s/s, but is usually written as m/s2.


When velocity is a-changin’…



Examples Understanding Motion



Old Blue Physical Science Textbook: Page 308 Problems: 2, 4, 5, 19 - 27.

PRACTICE

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Journal Entry: All Motion Is Relative

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