Monday, September 23, 2013

H Physics

Warm UpFind the a and Δx for the velocity vs time graph

Standards: 1a Students know how to solve problems that involve constant speed and average speed.

Learning Objective: SWBAT understand their mistakes from the last exam and rework the problems. Agenda: 1. Warm Up2. Correct HW3. Take Quiz P.24. Go over Test5. Begin Redoing Test Questions

Homework• Redo Incorrect Test

Questions• Quiz Friday• Make up Quiz Today After

School• Test Retake option available

until Oct. 4th

v(m/s)

t(s)

2

4

6

8

10

-2

-4

-6

-8

-10

4 8 12 16 20

Tuesday, September 24, 2013

H PhysicsWarm Up

If a golf ball starts with a speed of 2.0 m/s and slows at a constant

rate of 0.50 m/s2 , what is its velocity after 2.0 s? Standards: 1a Students know

how to solve problems that involve constant speed and average speed.

Learning Objective: SWBAT read and understand and interpret information presented graphically Agenda:1. Warm Up2. Review HW P.43. Correct Quiz P.24. Review Test P.2

HomeworkQuiz FridayRedo Inccorect Test Problems P.2Graphing Worksheet P.4

Wednesday, September 25, 2013

H Physics

Warm UpP.4 Draw a x vs t graph of an object

that

1. accelerates +2. Then stops abruptly3. Then rolls forward slowly

with a constant vCome up with a scenario that could describe this motion.

Standards: Standards: 1a Students know how to solve problems that involve constant speed and average speed.

Learning Objective: SWBAT read and understand and interpret information presented graphically

Agenda: 1. Warm Up2. P.2 Graphing Notes3. P.2 Graphing Practice4. P.4 Interpreting Graphs

Problem5. P.4 Motion Equations6. Motion Equations

Practice

Homework• Quiz Friday• P.2 Finish Kinematics

Graphs• P.4 Solve acceleration

problems

P.2 A ball on a ramp starts from rest and speeds up to 20cm/s in 0.75s. What is the acceleration?

Thursday, September 26, 2013

H Physics

Standards: Standards: 1a Students know how to solve problems that involve constant speed and average speed.

Learning Objective: SWBAT Agenda: 1. Warm Up2. Correct HW3. P.2 Analyzing Graphs4. P.4 Practice Solving

Constant Acceleration Problems

Homework• Study for Quiz• P.2 Graphing• P.4 Acceleration

Warm UpP.2 Draw a x vs t graph of an object

that

1. accelerates +2. Then stops abruptly3. Then rolls forward slowly

with a constant vCome up with a scenario that could describe this motion.

P.4 Find the initial velocity of a train that accelerates at 4m/s2 for 10 seconds and reaches a top speed of 28 m/s?

Friday , September 27, 2013

H PhysicsStandards: Standards: 1a Students know how to solve problems that involve constant speed and average speed.

Learning Objective: SWBAT score at least 80% on Quiz 4

Agenda:1. Warm Up2. Review Homework3. Take Quiz4. Practice with eqns of

motion

HomeworkExtra Credit scenario drawing due MondayQuiz Retake Monday After SchoolLast week to do test retake after School: Last days=Monday&Wednesday

Warm UpP.4 How far did a dune buggy travel to get

to the first set of dunes if it accelerated from its 40km/hr speed on the highway at

a rate of 5km/hr2 for 12seconds?

P.2 What is the area under the v vs t graph equal to? and What does the slope of the v vs t graph equal to?

Analyzing GraphsIn Physics there are three main purposes for drawing a graphical representation of motion.

2. To find its slope.

These are the main reasons to make a graph in physics. There isn’t very much more information a graph can provide you, so if you are EVER going to make a graph, you will need to find one or all of these three things, else it is pointless.

3. To find the area under the curve. Area of a triangle=(base*height)/2Area of a rectangle=Length*Width

1. To find its equation. y=mx+b, or another equation

Displacement vs. Time Graph

x(m

)

t(s)

10

20

05 1

0

1. Find the velocity from 0 to 4 s.2. Find the velocity from 4 to 8 s.3. Find the velocity from 8 to 10s.4. What is the equation of the line segment that begins at 4 s and ends at 8 s5. What is the area under the curve from 0s to 4s?

Below is the motion of a radio controlled car

Velocity vs. Time Graph

v(m

/s)

t(s)

10

20

05 10

1. What is the speed of the car at 4s?

2. Find the equation of the line segment that goes from 6s to 10s.

3. Find the acceleration from 4 to 6 s.

4. Find the acceleration from 6 to 10s.

5. Find the displacement from 4s to 6s.

6. Find the displacement from 0 to 4 s

This shows the change in motion of a radio controlled car.

Symbols, units and equations Study Guide--distance (d), displacement (Δx) units: meters (m)--speed (vs), velocity (v) units: meters per second (m/s, km/hr)--acceleration (a) units: meters per second squared (m/s2,km/hr2) --time (t or Δt) units: seconds

Equations:,

Relationship Between x vs t, v vs t and a vs t

graphsDisplacement vs. time graphs 1. Situation 1

i) the object is not moving

ii) the object’s velocity is 0 iii) the object’s acceleration is 0

2. Situation 2 i) the object is movingii) the object’s velocity is constant

iii) the object’s acceleration is 0

3. Situation 3i) the object is movingii) the object’s velocity is changingiii) the object’s acceleration is constant

Δx

Δt

Δx

Δt

Δx

Δt

Δx

Δt

Δx

Δt

Using an x vs t graph to create a v vs t

graph

t(s) x(m)

0 0

2 3

4 6

6 9

8 12

10 12

12 12

14 13

16 14

18 15

20 16

1. Take 3 minutes and sketch a graph from the adjacent table.2. To use this position vs time graph that you drew to find a velocity vs. time graph, first find the slope of each section of the graph3. Make a table of points, velocity vs time.

t(s)

x(m)

3

6

9

12

15

4 8 12 16 20

v(m/s)

1.5 0 0.5

t(s) 0-8 8-12 12-20

Practice Analyzing Graphs H

1. For graph 1 find the velocity from 0 to 9 hr, 12-18hr, and 21-27hr. 2. For graph 2 find the acceleration from 0 to 6hr, 6-8hr, 8-12hr, 12-

16hr, and 16-20s and the displacement from 8-12s*3. For graph 3, use your v vs t graph to find the a vs. t graph and the x

vs t graph.

t(hr) x(km)

0 0

3 5

6 10

9 15

12 17

15 19

18 21

21 24

24 27

27 30

t(hr) v(km/hr)

0 0

2 -2

4 -4

6 -6

8 -12

10 -16

12 -20

14 -20

16 -20

18 -10

20 0

1.2. 3.

t(s) v(m/s)

0 0

5 15

10 30

15 45

20 50

25 55

30 60

35 65

Identifying the motion from graphs. Four cars racing on a straight line track had motion described by each of the graphs below. Make a rough sketch of the race that shows the start and the final results. Each car is timed over equal time periods. In other words each graph ends at the same time.

Δx(m)

t(s)

x(m)

t(s)

x(m)

t(s)A

B

x(m)

t(s)

C

D

More on Accelerated Motion

Right now we use and when we solve problems with accelerating objects.

Now we have some new equations. One will make solving some acceleration problems easier.

One will allow us to solve a bigger variety of problems

Specifically we will be able to solve problems involving falling objects and a larger variety of problems where objects are slowing down and speeding up.

In class practice

A car traveling at 91.0 km/h approaches the turnoff for a restaurant 30.0 m ahead. If the driver slams on the brakes with an acceleration of -6.40 m/s2, (A) how long will it take for the car to stop? (B) What will be the car’s stopping distance.• Write down the Givens: 2 minutes• Draw the Diagram 3 minutes• Choose the equation 1 minute• Solve the problem 3 minutes.

Constant Acceleration Practice H

1. Which formula would you use to solve the following pr problems? Explain why. :

2. Solve problems a & b. 3. Find the uniform acceleration that causes a car’s velocity to change from 32

m/s to 96 m/s in an 8.0s period. 4. A car with an initial velocity of 22 m/s is accelerated uniformly at the rate of

1.6 m/s2 for 6.8s. What is its final velocity? 5. A child throws a ball down a hill at 5m/s and rolls down the hill with a

constant acceleration of 2.0 m/s2. If takes the ball 4 s for the ball to run into a wall at the bottom of a hill, how far did it roll before it hit the wall?

6. A race car can be slowed with a constant acceleration of -11m/s2. If the car is going 55m/s before it slows. How long does it take before the car stops?

7. *A dragster starting from rest accelerates at 49m/s2. How fast is it going when it has traveled 325m?

vf 0 m/s

vi 40 m/s

Δx not given

a -3 m/s2

t ?

vf not given

vi 20 m/s

Δx ?

a -3 m/s2

t 4.5s

ab

Constant Acceleration #2 H

1. A car accelerates from rest at a rate of 2.0 m/s2 for 22 seconds. How far does the car travel while accelerating?

2. A car accelerates from rest at 1.0 m/s2 and covers a distance of 500.0 m. How long did it take?

3. A boat accelerates at 0.5 m/s2 until it reaches 35 m/s. If its initial velocity was 5.0 m/s, how long did it take?

4. A car covers a distance of 400.0 m in 20.0 s. What was the car’s acceleration?

5. What was a motorcycle’s acceleration that went from 0 to 40 m/s is 5.2 seconds?

6. *A plane speeds up from rest to 270 m/s in 40 seconds How far did the plane travel? Hint: use both motion equations.

Constant Velocity & Acceleration C:

Lets make our own word problems:

To create a word problem answer the following questions.1. Which equation do you want this problem employ (use)? Ex.2. Which letter in the equation do you want to make your unknown? Ex. t=?3. You get to make up numbers for all other letters in the equation.

Ex. Δx=0.7m, a=4m/s2, 4. What object do you want to feature in your problem? Ex. baseball.5. Now construct a setting or a scene for the motion to happen in.

Ex. During a game a pitcher winds up and accelerates a baseball. If the pitcher accelerates the ball during his 0.6 meter long windup at 4m/s2, how long did the pitchers windup take? 6. Now you’re done. Solve it! Find the Givens and Draw a diagram

For Homework Make 2 Word problems and solve them. Make 1 for each equation.

Honors Acceleration Practice C:

Lets make our own word problems:To create a word problem answer the following questions.

2. Which equation do you want this problem employ (use)? Ex.3. Which letter in the equation do you want to make your unknown. Ex. t=?4. You get to make up numbers for all other letters in the equation.

Ex. Δx=0.7m, a=4m/s2,

1. What object do you want to feature in your problem? Ex. baseball.

5. Now construct a setting or a scene for the motion to happen in.

Ex. During a game a pitcher winds up and accelerates a baseball. If the pitcher accelerates the ball during his 0.6 meter long windup at 4m/s2, how long did the pitchers windup take?

6. Now you’re done. Solve it!. Write Your Givens. Draw Your Diagram.For Homework Make 2 Word problems and solve them. Make 1 for each equation.