Tuesday, November 12, 2013

Physics

Warm UpWhat will the Force Meter

read if a 20 g, 50g, and 70 g object are all hung from the Force Meter? Your answer

should be in Newtons.Standards: 1d Students now that when one object exerts a force on a second object, the second object always exerts a force of equal magnitude and in the opposite direction (N’s 3rd Law)WHST.9-12.2  Write informative/explanatory texts, including the narration of historical events, scientific procedures/ experiments, or technical processes. (HS-PS2-6)

HomeworkWork on Graphing Worksheet

Agenda1. Warm Up 2. Finish Tug of War Lab3. Begin Kinematics Boot Camp: Graphing

Wednesday, November 6, 2013

PhysicsWarm Up

If a giant kicks Jack from the beanstalk with a Force of

10,000 N, how much Force did Jack apply to the giant when the giant’s foot made contact

with Jack’s body?

HomeworkP.3 Day 1 Graphing

Standards: Review For Kinematics ReTest

Learning Objective: SWBAT will understand the process of solving problems.

Agenda: 1. Warm Up2. Review Tug of War Lab

Thursday, November 7, 2013

Physics

Warm UpA car is moving at a

constant speed. Draw the scenario and identify at

least 2 Force Pairs acting on the car.

Standards: 1a. Review for Kinematics ReTest

Objective: SWBAT understand the problem solving process

HomeworkP.3 Day 1 GraphingP.6,P.7 Day 2 Problem Solving

Agenda: 1. Warm Up2. Review Tug of War Lab3. Review Day 1 Graphing4. Kinematics BootCamp

Friday, November 8, 2013

Physics Standards: 1c Students know how to apply F=ma to solve one-dimensional motion problems that involve constant forces.

Learning Objective: SWBATAgenda: 1. Warm Up2. P.3 Review HW3. P.3 Take Test4. P.6,7 Review Graphing5. P.6,7 Problem Solving Homework

Finish Graphing & Problem Solving Worksheets. Due Monday

Warm Upt(s) v(m/s)0 42 94 14

Graph, make the best fit line, and find the slope

Symbols, units and equations Study Guide

Equations:

Constant Velocity

Constant Acceleration

1.

2.

The Two equations of Motion The Two equations of Motion for Falling Objects ag=-9.8m/s2

Forces

Symbol Units

t s

v m/s

a m/s2

F kgm/s2 or N

Δx m

Force Meters• Force Meters• Objective: Students construct rubber band force-meters to aid in the

investigation of forces and Newton’s 3rd Law. See Figure 5.• Engage• Watch Video:• Why do objects weigh less on the moon?• What else might affect the weight of an object?”• Explore• How can we use a rubber band to actually determine the weight (the force due to

gravity) of an object?• Explain• In order to actually put numbers on our force meters, we have to know the

formula for figuring put the amount of gravitational force Fg from a certain amount of mass m.

• The formula is Fg = mg (or W = mg)• Elaborate• How is this related to Newton’s 2nd Law, Fnet = ma?”• Evaluate• Students should now create an accurately labeled scale on their force-meters,

displaying the applied force in units of Newtons.• Problem Set: #F4 Fg = mg.

Figure 5. Rubber band force-meter

Types of Forces• From your book p. 94 Table 4-2

Force Symbol Definition Direction

Friction Ff Resistive Force. Comes from rubbing against or sliding across surfaces.

Parallel to the surface and opposite the direction of sliding

Normal FN The force exerted on an object by the ground, a table, a platform, or any surface.

Perpendicular to and away from the surface.

Spring Fsp Restoring Force. The push or pull a spring exerts on an object.

Opposite the displacements of the object at the end of the spring.

Tension FT The pull exerted by a string, rope, or cable when attached to something.

Away from the object and parallel to the string, rope, or cable at the pont of attachment.

Thrust, Applied Force Fthrust,Fap A general term for the forces that move objects such as rockets, planes, cars and people.

In the same direction as the acceleration of the object.

Weight Fg Attractive Force of two objects due to gravity. Usually Earth and and object

Straight down towards the center of the earth.

Air Resistance/Drag FAR Resistive Force, comes from air/wind hitting moving objects

Opposite of Motion

F1b

Newton’s 2nd Law Problems

 1. If a student accelerates on his/her bicycle at 4m/s2, and the student has a mass of 77 kg. How much force does s/he apply to the bicycle?2. Find the weight of the following people: Rickey is 100 kg, Manny is 150kg, and Donna is 65kg and the acceleration due to gravity is 9.8m/s2. 3 How much force does a baseball experience if the baseball bat accelerates the ball at 8m/s2 and the mass of the baseball is 5kg? 4. How much force would a 10kg baseball experience if the bat accelerated the ball at 20m/s2?5. What is the mass of a bullet that accelerates at 100m/s2 by a 12 N Force when shot out of a gun?6a. Thrust from a rocket’s engine equal to 100,000 N launches a shuttle with a mass of 10,000 kg into the air. What is the rockets acceleration? 6b*If the acceleration due to gravity is 9.8 m/s2 will the rocket be able to escape the earths atmosphere?7. A wide receiver (90 kg) is tackled after catching a football by one of the safeties (99 kg). The safety applies a force of 250N? How fast did the receiver decelerate? (Be careful when you choose which mass to use.)

#F2

Newton’s 2nd Law 2 #F3

1. What does Fnet mean?2. What is the equation Newton’s 2nd Law.3. What do you change from Newton’s 2nd Law equation in order to

find weight (W or Fg) ? 4. Find the net force of mini car racing if friction is 20N, the

accelerator supplies 50N, and air resistance is slowing it down by 2N.

5. If the car from problem 4 has a mass of 1 kg, what is the car’s acceleration?

6. Which direction does Gravitational Force push?7. Describe the Normal Force? 8. Friction acts in which direction? 9. If an object is flying northeast, which direction is air resistance

pushing?10.Find the mass of an object if it accelerates at 2 m/s2, when 20N of

Force pushes it.

Weight: Problem Set #F4

1. What is the weight of a 60kg person? 2. What is the weight of the 10kg object? 3. A 4kg and a 6kg object fall from a plane. How much more

Force will the 6kg object hit the ground with than the 4kg object?

4. The 4kg and 6kg object both fall from a plane 10,000 m above the ground. Which one will hit first?

5. Find the weight of a 300g object (in Newtons)?6. An object weighs 10,000N on an unknown celestial body, but

only has a mass of 0.5 kg. What must be the acceleration of gravity on this celestial body?

7. Find the acceleration due to gravity on the moon if gravity on the moon is 1/6 of earths 9.8 m/s2?

8. Use your answer from the previous problem to find the weight of a 90 kg object on the moon.

9. Find the mass of a plane whose weight is 4x105N?10.If it takes 2s for a 10kg object to fall 100 m from rest on an

unknown planet, what is the planet’s acceleration of gravity?

Student Learning Survey1. Before taking the test, how confident did you feel about your understanding

of Kinematics (motion)?2. After taking the test, how confident did you feel?3. Do you still try to succeed in this class? If not, what made you stop trying?4. I learned Physics the best when Mr. Ancalade did…….5. Do you do homework? If you do, does it help? If you don’t, why don’t you

do homework? 6. If you did not turn in the cart and mass lab, why didn’t you? If you did not

complete any portion of the lab, what was the reason? 7. I spend _____ minutes on Physics homework per night.8. I spend ______ minutes studying for tests.9. I spend ______ minutes studying for quizzes. 10. Is it helpful when Mr. Ancalade does problems on the board? If yes, explain

how it helps. If no or not really, what are the reasons it doesn’t help or only helps a little?

11. When I don’t understand how to do something in the class, what do I do? If you don’t ask your peers or myself, what are your reasons?

N’s 3rd Law: Tug-of-

War

• Figures 6 (a) and (b): A student and a partner each pull on the opposing force-meters and observe that they show the same reading. In the second scenario, one student holds his force-meter still, while the partner pulls his force meter to the right.

• Figures 7 (a) and (b): Students predict the reading on the force meter in each of the two scenarios depicted prior to testing.• Engage• What will happen to the motion of each chair when one of the students on the rolling chair pushes the other student on the rolling chair. Will

it matter which student pushes? Justify your answer. Tell me your reasoning. • Explore• Students attach their force-meters with rubber bands or string and record…

o the reading on each force-meter when both students pull (Figure 6 a.)o the reading on each force-meter when one student keeps his force-meter stationary while the other student pulls (Figure 6 b.)

• Explain• Newton’s 3rd Law mini-lecture• Elaborate• Recreate the Figures 7(a) and (b). Write predictions for the force-meter readings for each of the two scenarios in Figure 7 . • Next, test your predictions, discuss your results in a group and be ready to participate in a discussion about these results. • Evaluate• Newton’s 3rd Law Assignment: #F5 Due Monday

To get a Full 10 pts. complete every section with questions. That does not include the explain section (which is lecture) or the Evaluate Section (I will grade this section separately) Write on a separate sheet.

Newton’s 3rd Law Notes

Newton’s 3rd Law:Definition: For every action (Force) there is an equal and opposite reaction (opposing Force)

Equation

Where FBA is the Force of B on Aand FAB is the Force of A on B

Example1.An object on a table is pushing down on the table because of gravity and the table is pushing up on it with normal force.2. The Force of gravity occurs when there are 2 masses, each of them pulling on each other with an equal and opposite force.3. Friction and a Car’s tires.

Non-ExampleTrying to move from one point to another in space by waving your arms and legs furiously.

1. Using your Engage Experience, define Newton’s 3rd Law - 3 minutes.2. Discussion - 2 minutes

B A

FBA FAB

FBA = -FAB

Notes 5 mins

#F5

Modeling the Graphing Process

Step One – label each axis with the symbol and the units being represented by the graph.

1st column x-axis, 2nd column y axisStep Two – Create your x and y axis scales. To create a scale(your numbering system on the graph) look at your smallest and largest data points. Then pick a number sequence (ex. 1,2,3,4 or 2,4,6,8) that will allow all of the points to fit on your graph. Step Three – Plot the Points. Step Four – Make a best fine line. It has to be straight and you need to make it go through the center or through the average of your points. See board for more explanation.Step Five – Find the slope of the graph. Step Six (Honors Only) – Find the equation of the graph by substituting your data into the formula y=mx+b

Physics Problem Solving ProcessStep 1: Read the problem twice. Answer: Is the object in the problem traveling at some average or constant speed or is the speed changing or acceleratingStep 2: Look at the group of equations that applies to your situation: Constant Velocity or Acceleration. Then begin to write down the givens and pick their symbols based on the symbols you find in the equations.Step 3: Draw a diagram using the conventions we’ve learned. Be sure to represent all of the givens in your diagram. Step 4: Next pick your equation. The equation should only have one symbol that you don’t know. If it has more than one either pick a different equation with only one, or you may need to think about using another equation in addition. Step 5: Use the equation/s that you’ve picked, plug in the givens (don’t forget to include units) and solve for your unknown.

Step 1: Read the problem twice. Answer: Is the object in the problem traveling at some average or constant speed or is the speed changing or acceleratingStep 2: Look at the group of equations that applies to your situation: Constant Velocity or Acceleration. Then begin to write down the givens and pick their symbols based on the symbols you find in the equations.Step 3: Draw a diagram using the conventions we’ve learned. Be sure to represent all of the givens in your diagram. Step 4: Next pick your equation. The equation should only have one symbol that you don’t know. If it has more than one either pick a different equation with only one, or you may need to think about using another equation in addition. Step 5: Use the equation/s that you’ve picked, plug in the givens (don’t forget to include units) and solve for your unknown.

Physics Problem Solving Process