Speed, Velocity and Graphs

Get colored pencils are multiple colored highlighters if you have them

Review: Speed vs. Velocity

• Speed describes how fast something travels in a given amount of time

• Velocity is a vector quantity that describes how fast and in what direction and object is moving

• Vector quantities can be shown on diagrams with arrows.

• The length of the arrow represents the relative speed and the direction it is pointing represents the direction of movement

Reading Graphs

Quick graphing review:

• X axis is the horizontal axis, this is the independent variable

• Y axis is the vertical axis, this is the dependentvariable

How do you Graph Motion?

General Understandings - 1

For distance vs. time graphs –

If we look at the graph shown, you can see that the time in hours is along the horizontal, and the distance in miles is on the vertical axis. This graph represents a journey that Jan took, in travelling to Dallas and back, from Austin.

Distance Time Graphs

• Think of these as “journey” graphs!!

Watch this video

• Distance – time video: https://www.youtube.com/watch?v=9LQdLDDEJ1g&feature=youtu.be

Packet:

Packet Instructions:

• Read and highlight important information in the packet. I will demonstrate what this means.

• Work any “problems” you come across.

• Stop when you get to page 7.

• We will go over this section of the packet together before continuing

No Motion

• Time is increasing, but distance does NOT change. It is

NOT MOVING…NO MOTION…AT REST.

CONSTANT SPEED• Time and distance are

INCREASING at a constant rate. This

graph shows CONSTANT

SPEED.

CONSTANT SPEED

• This graph is the same as above, but shows a change in direction (meaning

the object is headed back to the starting point). This graph

also shows CONSTANT SPEED.

FASTER SPEED

• A steeper line shows greater

distance traveled in a given time.

The STEEPER THE LINE, the HIGHER THE

SPEED.

ACCELERATION• In a given time,

the distance the object moves is getting larger, it

is ACCELERATING.

The curve upward shows

an INCREASE in SPEED.

DECELERATION• This graph is

the same as above, but the

curve downward

shows a DECREASE IN

SPEED or DECELERATION

.

Putting it all together

Main Points

• A straight diagonal line shows constant speed.

• A curved line shows average speed.

• A horizontal line shows no motion.

• Time is on the x-axis, distance is on the y-axis.

• The steeper the line, the faster the motion.

Demo!

• Gizmo Lab Demo:

Speed/Velocity Time Graphs

General Understandings - 2

Speed (or velocity) vs. time graphs

• The steeper the gradient of the line (the slope), the greater the acceleration (a bigger change in speed in the same time).

Speed Graphing Videos

• Speed – Time Graphs

• Distance vs. Time Graphs

Demo!

• Gizmo Lab demo:

Packet Instructions:

Speed Graphs section: p. 7 - end

• Read and highlight important information in the packet. Work any “problems” you come across.

• When finished, make sure you have the HW.

• We will go over this section of the packet before continuing

HW – Juan’s Big Race