Monday, December 19, 2016

Activity 69: Energy Practice Problems



Energy Practice Problems


Please answer the following question in this document.  The answer key is on the last page.

While all the questions are good,  you might want to focus on the following ones first.

3, 5, 8, 10, 11,  13, 14,  17,  18,  21, 23, 24,  27, 29, 30,  34,  38,  40,  41,  42,  45, 46, 47 , 48, 49, 50, 53,  54,  58, 60,  63,  64, 69, 70, 71,  74



Wednesday, December 14, 2016

Activity 68: Energy Questions


Please answer these questions on page 260 on the textbook.


13, 15, 18, 20, 21

When you are done check your answers here..


Monday, December 12, 2016

Activity 69: Springs Pendulums & Power Questions



Speed of a Pendulum

A pendulum consists of a ball at the end of a massless string of length 1.4 m. The ball is released from rest with the string making an angle of 20 degrees with the vertical. What is the maximum speed of the pendulum? 


Potential Energy of a Spring

PEs = ½ kx2




Please answer these questions on page 260 on the textbook.


22, 23, 27,

When you are done check your answers here..


24, 25, 32, 33, 37, 38




Activity 67: Energy Notes

Energy Notes

Total Work =  Fd Cos(θ)

KE = ½ mv2

Wnet = ΔKE  = Δ½ mv2 = FnetdCos(θ)

PE = Potential Energy

ΔPE = mgh

Conservative Forces
A “Conservative Force” is once for which work depends only on the starting point and ending point.

We can define potential energy for any conservative force.

PEg = mgh
PEs = ½ kx2

Mechanical Energy = KE + PE

Conservation of Mechanical Energy

When only conservative forces act then:
KEI + PEI = KEf + PEf
Or  KE + PE = constant

Nonconservative forces:
KEi + PEi  + Wnc = PEf + KEf
Wnc = ΔKE + ΔPE

Conservation of Energy

Other forms of energy -> electric, chemical, radiant, nuclear & thermal.

KEi + PEi  + Wnc + OEi = PEf + KEf + Oef

1 kcal = 4184 joules


Power

Power is the rate at which work is done.

Power = Work/Time = Fd Cos(θ)/Time


Units in Watts.

1 Watt= 1 J/s

1hp = 746 Watts







Link to Gravitational Potential Energy Questions








Thursday, December 8, 2016

Activity 65: Introduction to Work




Work = Fd cos(theta)

F = Applied Force

d =  the displacement of the object

theta = the angle between the Applied Force the the Direction of movement


Work is measured in Joules.

1 Joule = 1 Newton meter = 1 kg m^2/s^s

1 J is small.  ~ lifting a 100 gram apple 1 meter.

Other energy measures:  1 calorie = energy need to heat 1 g of water by 1 degree Celsius
                                        1 calorie = 4.184 J
                                       
                                         1 food calorie (kcal)  = 4185 J



Work is the means of energy transfer.



Net Work is the sum of all work done on a system:   Wnet = Fnet d cos(theta)



Net Work is the area under a Net Force vs Displacement Graph.

If the Fnet is in the same direction as the motion then Wnet = Fnet d

Since Fnet = mad

Wnet = mad


v^2 = v0^2 + 2ad

a = (v^2 -  v0^2)/(2d)

Wnet = m( (v^2 -  v0^2)/(2d))  (d)
         

Wnet = 1/2 mv^2 - 1/2 mv0^2

1/2 mv^2 = KE


Wnet = change in KE of the system


If Wnet is zero then there is no change in kinetic energy.


2 kinds of Mechanical energy

   KE = 1/2mv^2

   PE = mgh

Conservative Forces: A force is conservative depends on the starting point and ending point of an object.

NonConservative Forces: A force whose work depends on the path taken.  Friction is a good example.

Conservation of of Mechanical Energy

When on conservative forces are involved:

Wnet = 1/2 mv^2 - 1/2mv0^2  = delta KE

Wnet = delta KE

-deltaPE = delta KE

or

PEi + KEi = PEf + KEf




Read section 7.1 and answer questions 1 -> 8 on page 260.   Review your answers here.

Tuesday, December 6, 2016

Activity 45: 2 Body Problem Answers



Q1:  a = 4.46m/s/s
        Force = 7160N

Q2: a = 1.32 m/s/s
        Force = 15.8N

Q3: a = .215 m/s/s
       Ft = 1811N
     

Q4:  A to B Force = 316N
        C to D Force = 276 N

Monday, November 28, 2016

Activity 42a - Forces in Motion Problem Set #1





Activity 40.10 - Read these pages  on gravitational mass and the conclusions from the lab.

Pick up a paper copy of Forces in Motion Problem Set #1, and complete it, (you can ignore questions "18. f" and "18. g").

When you are done check your answers here.





Activity 38: Newton's 3rd Law - Picking the right system



Lecture Slides

38.10 : Example problems

Activity 42: Accelerating with Newton Lab



Read the Accelerating with Newton Lab, page 86 - > 95 in this document.  Notice this lab has three procedures.  Each procedure has its own analysis section.  You can write a single conclusion paragraph but it should contain your conclusions from each procedure.

Here is a link to the experiment logger-pro template file

Use this template for your lab write-up. You simple need to follow the procedures outlined, answer the questions in the analysis sections and write a conclusion.






Tuesday, November 22, 2016

Activity 41: Calculating Tension



Activity 58.10

Pick up a paper copy of this handout on calculating tension.

Activity 58.20

Pick up a paper copy of these tension problems  When done check your answers here.





Thursday, November 17, 2016

Wednesday, November 16, 2016

Activity 33 : Forces in 2D PS #3




Activity 47.10

Pick up a copy and complete these two seminar problems.


When done check your answers here.


Activity 47.20

Pick up a copy of "Force Be with You Problem Set 3".

When you are done,  done check your answers here.


Activity 47.30

Pick up a paper copy of this activity and complete it.

Put your answer in this form.

Monday, November 14, 2016

Activity 32: Forces in 2D PS #2




Pick up, and review,  a paper of this write-up on "Force Diagrams and Equilibrium"

Pick up a paper  copy of "Force Vectors in 2D Problem Set #2" and complete the problems.

When done check your answers here.

Activity 31: Introduction to Forces in Equilibrium




Activity 43.20 - Forces in Equilibrium


Newton's first law of motion is often stated as
An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.  
So an object that is not moving, or an object that is moving at a constant velocity will not change its motion unless an unbalanced force is applied to it.  The term unbalanced force is simply a way of stating that if I add up all the forces on an object then that total force  is not equal to zero.  If however the forces on an object are in balance then the net force is zero and the object's motion or lack of motion will not change.

Equilibrium

An object is said to be in linear equilibrium if the net force on the object is equal to zero.  Another way to state this is,  the net force on an object which is not accelerating must be equal to zero.

Forcenet = 0 if an object is in equilibrium ( it is not accelerating).

Newton's 2nd law is often stated as Fnet = Mass X Acceleration.

As you can see from this equation if an object's acceleration is equal to zero (it is in equilibrium) then its Fnet = 0.

If the net force on an object is zero it then follows that:


  • All of the forces in the horizontal direction must add up to zero.
  • All of the forces in the vertical direction must add up to zero.
You may wonder why we care about the summation of an object's horizontal and vertical vectors adding up to zero.  The can be summarized as:

  • The main technique to adding vectors is to add their horizontal and vertical components together.  If we know an object is in equilibrium, then we know the summation of its horizontal and vertical components must also equal zero.  Otherwise it would be accelerating either horizontally or vertically or both.



Watch this video to help you understand how you can use the concept of forces in equilibrium to calculate the forces on an object.



Activity 43.30 Vector Addition Review




Answer to following problems 5,6,7,9 &10:









Activity 43.40 Vector Components

Pick up a paper copy of this worksheet.  Review the drawings on the first page and answer the questions on page 168.   Check your answers on the last page of the document.








Activity 30A: Mystery Mass Lab




Monday, November 7, 2016

Assignment 29 - Introduction to Newton's Laws




Force  - Any push or pull on an object

Dynamics  - Study of forces that cause objects or systems to move.

Mass - A measure of the amount of stuff in an object.  The more mass an object has,  the more it is resistant to a change in its motion. An object's resistance to change in motion is called inertia and this inertia is directly proportional to an object's mass. 



Newton's First Law of Motion

A body at rest remains at rest, or, if in motion will, remains in motion at a constant velocity unless acted on by an external force.  

The acceleration of a system is directly proportional to and in the same direction sat the net external force acting on a system, and inversely proportional to its mass.

              Fnet = ma  


Units of force: 1 Newton is the force necessary to to acceleration 1kg at a rate of 1 m/s/s.

            1N = 1kg m/s/s


Weight is a force where g is the acceleration due to gravity.

             w = mg

The weight of a 1 kg object is :
            
                    w = 1kg x 9.8 m/s/s = 9.8N

Assignment 29.10

Types of forces
Pick up a paper copy and review the list of "contact" and "at a distance forces".  Pick up a paper copy and review the list of forces.

Free Body Diagrams
Pick up a copy of this document on free body diagrams and answer it's question.  When done, review your answers here.

Assignment 29.20

Read pages 127 - 136 , sections 4.1, 4.2, 4.3 in the textbook


Answer questions 
1,2,3 , 5 on page 161 in the textbook.  Review your answers here.






Sunday, October 30, 2016

Assignment 25: Relative Velocity



Activity 25.05

Pick up a paper copy of this document on relative velocity and read.

Activity 25.10

Read Section 3.5 in the textbook.

Do the following  relative velocity practice problems.


Check your answers here.


Activity 25.20
Pick up a paper copy and run and answer the questions in this Riverboat Simulator.   When done check your answers here.


Activity 25.40

Pick up a paper copy of the Activity 17.40 Problem Set.  When done check your answers here.


Activity 25.50

Do problems 27 -> 30 on page 159  in the Section 6.3 hand out.


Activity 24: 2D Projectile Problems: James Bond & Field Goal Kicking




Complete these questions and check your answers here....


Thursday, October 27, 2016

Activity 23: Fenway Park & Airplane Problems




Pick up a copy of the  Fenway Park and the Bombing Run  problems.

When done check your answers here and here.


Activity 22: Projectiles Launched at an Angle





Activity 38.20

Obtain a copy and review the  chart in this document highlighting the computation of the horizontal and vertical components of an object launched with velocity V0  at an angle  in this document.  Notice the use of Sine and Cosine functions to compute the components.

Review the following problem solving strategy:

Problem Solving Strategy

1. Make a sketch of the situation and label all given and unknown quantities.

2. List all of the equations that apply to the problem.

3. Determine what variables are known and needed.

4. Substitute the given quantities into the equation using proper units.

5. Solve the equation, carrying units throughout the problem.


6. Check your answer to make sure it makes sense.


Use the strategy to complete the answers to problems # 4, 5 and 6 in the above document and check your answers here.


Monday, October 24, 2016

Activity 21C: Projectile Problems


Read Sections 3.1 and 3.4  in the  OpenStax Textbook. 

Answer problems 25, 26, 27, 34, 41 & 42 at the end of the chapter on page 123.

When done check your answers here.

21b: Projectile Seminar Problems

Activity 24.10

Try and solve the following  projectile problem.

A ball is launched horizontally off a 200m cliff, with a horizontal speed of 10 m/s.
How far from the base of the cliff does the ball land?

After attempting to solve this problem check your answer by watching this video on projectile motion.




In this packet of 5 seminar projectile problems complete the 1st problem (David vs Goliath) and review your solution with your teacher.


Complete seminar problems 2 - > 5 and review your answers here.







Friday, October 21, 2016

Friday, October 14, 2016

Activity 20: Acceleration Problem Sets 5 & 6


Activity 20.10
Pick up a copy of acceleration problem
 set #5 and complete these problems.  When done check your answers against this answer key.

Activity 20.20  

Pick up and complete a  copy of this acceleration Problem Set 6, and check your answers here.




Activity 19 More Acceleration Problems


Activity 19.10

Complete problems 41, 42, 44, 46, 51and 53 on pages 83-84 in the  OpenStax Textbook. 

When done check your answers here.....



Wednesday, October 12, 2016

Activity 18: Acceleration Problem Set 4

Activity 18.10


Read Section 2.6 & 2.7 in the  OpenStax Textbook. 

Answer the questions in this problem set. (obtain a printed copy from your teacher) When done check your answers here.





Activity 17A - Seminar Problems & Solutions

Activity 27.10





Remember:
An object in free fall is accelerating at 9.8 m/s^2 down all the time.

So an object tossed or hit upwards is slowing down at a rate of 9.8 m/s all the way up, and speeding up at a rate of 9.8 m/s all the way down.
  • At its peak,  an  object in free-fall has a vertical velocity of zero (for an instant). 
  • The motion of an free falling object tossed up is perfectly symetrical.  It takes the same amount of time to go up, as it takes to go down,  and it's speed going up is the same as it's speed going down at every vertical height.

Complete these two seminar problems on Free Falling bodies. (You do not need to do section f: "using logger pro"  on the second Romeo & Juliet problem) When done check your answers here.

    Tuesday, October 11, 2016

    Activity 16: Displacement as the Area Under the Velocity-Time Curve and Solving Non-Constant Acceleration Problems

    Activity 14B

    Watch this video which describes displacement as the area under a velocity-time graph.

    Read this document which reviews the concept that the area under a velocity-time graph  is the object's displacement.

    Activity 16.20
    Examination of the motion in a velocity time graph should help make clear why the equations of kinematic motion only apply in situations where the acceleration of the object is constant.  In situations however where an object's acceleration is not constant it is often possible to divide up the problem into sections where the acceleration in each section is constant and then apply the equations in each section to calculate the needed information.

    A good example of this is found in this link to a Student Driving Situation.  Solve the question posed in this exercise (ask your teacher for a paper copy) and compare your answer with this key.


    Activity 16.30

    Ask your teacher for a paper copy of Acceleration Problems Set #3.  Complete this problem set and compare your answers against this key


    Activity 16.40 

    You are ready to take this acceleration pre-quiz.  Compare  your answers with this key.





    Thursday, October 6, 2016

    Thursday, September 29, 2016

    Activity 10B: Acceleration vs Angle Lab






    Design and execute an experiment to determine the relationship between the angle of a ramp and the acceleration a cart has as it goes down the ramp.


    Materials

    Logger Pro & Motion Detector
    Ramp
    "Frictionless"  Cart
    Connection wires and clamps
    Protractor (or cell phone for angle)


    You lab report should contain the following sections:


    Purpose/Question:
    Procedure:
    Data: (including appropriate graph(s) )
    Analysis:
    Conclusion:
    Error Analysis:


    The lab report should be done google docs and shared with your lab partners and submitted to
    the class's google class room Acceleration vs Angle assignment.




    Lab report template






    Tuesday, September 27, 2016

    Activity 10: Introduction to Acceleration



    Activity 10.10








    Read Section 2.4 in the  OpenStax Textbook. 
    After reading this you should know: 
    • The difference between average acceleration and instantaneous acceleration.
    • Average Acceleration = Change in Velocity / Change in Time
    • Change in Velocity = Average Acceleration X Change in Time
    • Do these problems from the textbook, and check your answers here.

    Activity 10.15
    Answer questions 13,14,16, and 17 below.  
    Check your answers here....

    Activity 10.18
    Answer questions 16 -> 18 on page 82 in the textbook.   When done check your answers here.

    Activity 10.19
    Complete this East-West Work Sheet  and check your answers here