Chapter 3: Acceleration

Physics: Principles and Problems

• ACT/PSAE practice• Intro to acceleration–What does it mean in common language?–What does it mean to a physicist? (That’s you!)

• First equation of acceleration– A = v/t– Standard unit for acceleration: m/s^2

• Example Problem• HW: Acceleration WS #1– Be sure to convert km/h to m/s!

Agenda

• What is acceleration? When am I accelerating?

• Is acceleration a scalar or vector?• How do I solve a physics problem involving

Acceleration?• What does a position-time graph of

acceleration look like?• What are velocity-time graphs, and how can

I find distance travelled and instantaneous acceleration

Essential Questions for the Chapter

What does it mean to you in common conversation?

What is the book’s definition?

“Deceleration” is just acceleration in a negative direction

Acceleration

______ is riding their bike to school. They

Example Problem

1. You run the 100 meter dash with an average velocity of 8 m/s. How long does it take you to finish?

2. Make a position-time graph of the following motion diagram:

(Line shows meters)

(Hint: how long did it take to go 10 meters?) 3. If your car can accelerate from rest to 20

m/s in 4 seconds, what is its acceleration?

Bellringer

When you fall, do you fall at a constant rate or accelerated rate? How do you know? Use complete sentences (UCS).

Bellringer

Is acceleration a scalar or vector? How do you know? Use complete sentences (UCS).

Bellringer

Collect Reaction Time Lab Bellringer Introduce Acceleration Equation #2:

◦ THE MONSTER!◦ df = ½ a* t^2 + Vyi * t + di◦ Example Problem

Acceleration WS #2◦ Due Wednesday

EQ: How does acceleration affect distance travelled?

Agenda 9/15

Already know: Acceleration = (Vf – Vi) / t How do we find displacement? Df = ½ a * (t)^2 + Vi * t + Di

◦ Df =◦ a = ◦ t =◦ Vi =◦ Di =

What kind of equation/relationship/graph is this?

Acceleration

If your car can accelerate at 5 m/s2, how long will it take the car to accelerate from 10 m/s to 25 m/s?

Bellringer

Bellringer Graphing Assignment Acceleration WS 2 pushed back to Thursday

(for this class only)

Agenda

Draw a position time graph of the following:◦ 1. An object travelling at a constant velocity◦ 2. An object that is not moving (start it at a

position other than zero so we can see the line)◦ 3. An object travelling that changes its velocity.

Make sure to label your axes!

Bellringer

Bellringer

Average Velocity WS corrections [10 min]

Reading Guide 3.1-3.2 [10 min]

Finish Acceleration ws 2

Agenda

Collect Acceleration WS 2 Lab: Speed Freaks 2.0

◦ Go to the FOOTBALL FIELD!

Essential Questions:◦ What does acceleration look and feel like?◦ How do we calculate speed and acceleration?

Agenda 9/21

Introduce ‘g’ ◦ -9.8 m/s^2

Hang Time Lab◦ Finish by tomorrow first thing!

Essential Questions:◦ Does gravity pull things down at a constant

velocity or accelerated? At what rate?◦ How does gravity affect how I jump?

9/25 Agenda

Collect Ch 2.2 Reading Guide Learn Breaking Distance Equation Problem Reading Trainer Accelerated Problem Poster Project

◦ Buy a poster this weekend. In fact, buy 5 posters.◦ Show Examples

Project: Make a parachute for an Egg◦ Make it out of anything.

Paper / plastic bags, newspaper String, tape, glue, staples Empty cartons for basket

◦ Project Rubric Next Week

9/26 Agenda

This equation is used when time is not involved (not given or asked for)

Vf^2 = Vi^2 + 2 * a * d Notice: no time! ______ is about to crash into _______. Their

velocity is ________. If the cars are ______m apart, what acceleration do they need to have to avoid a crash?

Braking Distance

What are our Equations?

CHAPTER 2 CHAPTER 3

Velocity = disp. / time◦ Vavg = Dd / Dt

◦ Constant Velocity means no acceleration.. Use this forumla!

Standard unit for velocity is m/s

A = Vf – Vi / t

Df = ½a*t2 + Vi*t + di◦ Shortcut: t = sqrt(2*d/a)◦ Only to be used when

falling and Vi = 0. Vf^2 = Vi^2 + 2 * a *

d

Acceleration due to gravity : g = -9.8 m/s2

◦ “fall, thrown, drop? Use g”

Collect Corrected Work ACT/PSAE Practice Distribute Problem Reading Trainer

Essential Questions: What are the common elements to solving a

physics problem?

9/29 Agenda

A ball rolls horizontally at 6 m/s. How long will it take the ball to cover 30 meters?

A ball rolls off of a table. It falls for 1 second before hitting the ground. How tall is the table?

Make a p-t graph of someone walking forward for 2 seconds, stopping for 2 sec, and backwards for 2 sec.

Extra credit: make a velocity-time graph of this too!

Bellringer 10/1

September 24

Bellringer Agenda

A football is thrown down field. It is caught at the same height that it was thrown. It is thrown at 20 m/s. How fast is it going when it is caught?

Write in 1-3 complete sentences HOW DO YOU KNOW?!?

Bellringer Interim Assessment

#1◦ Do not write on the test◦ You must bubble in

Name and ID◦ You MUST WRITE at the

top: “Hedden Period _” ◦ Pass back work

Go over the toughest assignment

Used for Right triangles only

Involves Sine, Cosine, and Tangent

Can be used to find an angle or side of a triangle by using two other parts of the triangle.

Pythagorean Theorem a2 + b2 = c2

SOH CAH TOA

Trigonometry

𝑆𝑖𝑛𝜃=𝑜𝑝𝑝h𝑦𝑝

𝐶𝑜𝑠 𝜃=𝑎𝑑𝑗h𝑦𝑝

𝑇𝑎𝑛𝜃=𝑜𝑝𝑝𝑎𝑑𝑗