Chapter 9 sec. 3 Acceleration Mr. Sapalicio Monterey Highlands Elementary School Physical Science

Everyone outside Do Try this Read the next 3 steps and then do…… 1. Everyone head outside, and line up on the cement and face the field. 2. Begin to walk slowly towards the soccer goals, and every few seconds walk a little bit faster. 3. DO NOT RUN, there is no prize for being there first. Please listen to my instructions when you get outside. Everyone outside

Changing Velocity A Balloon How would you describe its motion? What could you do to make it move? Describe any changes in the speed or direction as the balloon moved. This section will cover the changes in speed and direction. How is this an example of acceleration?

Changing Velocity Acceleration- the rate at which velocity changes with time. (speed up, slow down, change in direction over time) Acceleration is a piece of velocity. It tells you how velocity changes. (speed and direction) *In science acceleration refers to increasing speed, decreasing speed, or changing direction. How was the balloon an example of acceleration?

How can a car be accelerating if its speed is a constant 65km/h? Its change in direction.

On the left In 3 minutes draw me 3 pictures that show how an object can accelerate.

Finding Acceleration Acceleration= final velocity- initial velocity *To determine the acceleration of an object, you must find its change in velocity per unit of time.* Acceleration= final velocity- initial velocity time

Calculating acceleration Remember- velocity is measured in (unit of distance/unit of time) Example: m/s….. Or km/h……… or km/s….etc. And to find acceleration you must divide 2 velocities by time. So what does this mean? You will get acceleration=m/s-m/s s Making your final answer __m/s²

Practice If you are confident with how to find these answers……. Work on math practice page 353 #1,2 If you still need a 2nd look I will demonstrate how to find those answers in more detail.

Graphing acceleration *You can use both a speed vs. time graph and a distance vs. time graph to analyze the motion of an accelerating object.* focus is speed vs. time

Speed vs. Time graph Straight lines “up” tell us that speed is increasing. Straight lines tell us that acceleration is constant.

Speed vs. Time Graph What does the black line tell us. What does the green line tell us.

Graph analysis The black line tell us that the object is accelerating at a faster rate The green line tells us that the object is accelerating at a lesser rate.

How to graph acceleration Step 1. Find the acceleration of the object. A=fv-iv/ time Step 2. Use the acceleration answer as your slope Step 3.Begin to graph.

Math practice in science class Work on math practice on page 355 numbers 4 & 5. Graph number 4 (SPEED vs. TIME)