Project Pick a partner and build a pulley system with string, weight, and a spring scale. Pick a partner and build a pulley system with string, weight,

ProjectProjectPick a partner and build a pulley Pick a partner and build a pulley

system with string, weight, and a system with string, weight, and a spring scale. spring scale.

Switch with another group’s system Switch with another group’s system and see if you can predict the and see if you can predict the reading on the spring scale without reading on the spring scale without looking at it.looking at it.

Be able to explain how you were able Be able to explain how you were able to make your predictions.to make your predictions.

Lesson #45Lesson #45Topic: Problem solving with tensionTopic: Problem solving with tension

Objectives: Objectives: (After this class I will be able to)(After this class I will be able to)

1.1. Practice more complicated system Practice more complicated system and tension problemsand tension problems

1/2/07

Assignment: Corrected “Tension” due tomorrow!

Warm Up: Review Evaluation (Get out a separate blank sheet of paper and put your name at the top)

Review EvaluationReview Evaluation1.1. What is the tension in the string?What is the tension in the string?

2.2. What is the tension in the string?What is the tension in the string?

1kg

T=?

4kg

T=?Fa

Review EvaluationReview Evaluation

3.3. What is the normal force acting on block #2?What is the normal force acting on block #2?

4.4. What is FWhat is F1 on 21 on 2??


#1

#2

2kg

8kg


6.6. What is the acceleration of the system?What is the acceleration of the system?

7.7. What is the net force acting on each individual object?What is the net force acting on each individual object?

8.8. What is FWhat is F2 on 32 on 3 ? ?


#1#2

2kg8kg 4kg

#3Fa=28N


10.10. Find the net force acting on the block.Find the net force acting on the block.

11.11. Find T.Find T.

1kg

T=?The block is accelerating downward at a rate of 1m/s2.



13.13. What is the net force acting on each individual What is the net force acting on each individual object?object?

14.14. Find TFind T11..


6kg 4kg2kg

Fa= 18NT1 T2

Review EvaluationReview Evaluation1.1. What is the tension in the string?What is the tension in the string?

2.2. What is the tension in the string?What is the tension in the string?

2kg

T=?

2kg

T=?Fa


3.3. What is the normal force acting on block #2?What is the normal force acting on block #2?



#1

#2

1kg

5kg



7.7. What is the net force acting on each individual object?What is the net force acting on each individual object?

8.8. What is FWhat is F2 on 32 on 3 ? ?


#1#2

1kg6kg 3kg

#3Fa=30N


10.10. Find the net force acting on the block.Find the net force acting on the block.

11.11. Find T.Find T.

2kg

T=?The block is accelerating upward at a rate of 1m/s2.



13.13. What is the net force acting on each individual What is the net force acting on each individual object?object?



10kg 7kg1kg

Fa= 18NT1 T2

Normal force reviewNormal force review Tension at an angle Tension at an angle

Split T into x and y components.Split T into x and y components. Draw all other forces acting on the object.Draw all other forces acting on the object. Find FFind Fnetnet.. Find T.Find T. Find FFind Fnn..

T

30°10kg

Horizontal

acceleration = 2m/s2.

Practice with tension and Practice with tension and systemssystems

The Atwood’s machine.The Atwood’s machine.

Draw the forces acting on the system.Draw the forces acting on the system. Find the net force acting on the system.Find the net force acting on the system. Find the acceleration of the system.Find the acceleration of the system.

6kg

4kg

Practice with tension and Practice with tension and systemssystems

The Atwood’s machine.The Atwood’s machine.

Find the net force acting on each individual object.Find the net force acting on each individual object. To find tension, analyze the forces acting on only To find tension, analyze the forces acting on only

one object of the system.one object of the system.

6kg

4kg

T= ? T=

?

Lesson #46Lesson #46Topic: Lab: Atwood MachineTopic: Lab: Atwood Machine


1.1. Measure the acceleration of a simple system using Measure the acceleration of a simple system using a motion detector and compare the measured a motion detector and compare the measured value to a calculated value.value to a calculated value.

1/4/07

Assignment: Atwood Machine Lab due tomorrow!

Lab Task: Use system problem solving methods to write a net force equation and solve for an unknown variable.

BonusBonus

A rope is hung over a pulley. A rope is hung over a pulley. A 10kg block is hung from the A 10kg block is hung from the one side of the rope, and a one side of the rope, and a 10kg monkey hangs from the 10kg monkey hangs from the other side of the rope. The other side of the rope. The monkey climbs up his side of monkey climbs up his side of the rope with an acceleration the rope with an acceleration of 1m/sof 1m/s22. What happens to . What happens to the 10kg mass on the other the 10kg mass on the other side? side?

10kg

Warehouse DesignWarehouse Design You have taken a summer job at a warehouse and You have taken a summer job at a warehouse and

have designed a method to help get heavy packages have designed a method to help get heavy packages up a 15º ramp. In your system a package is attached up a 15º ramp. In your system a package is attached to a rope which runs parallel to the ramp and over a to a rope which runs parallel to the ramp and over a pulley at the top of the ramp. After passing over the pulley at the top of the ramp. After passing over the pulley the other end of the rope is attached to a pulley the other end of the rope is attached to a counterweight which hangs straight down. In your counterweight which hangs straight down. In your design the mass of the counterweight is always design the mass of the counterweight is always adjusted to be twice the mass of the package. Your adjusted to be twice the mass of the package. Your boss is worried about this pulley system. In boss is worried about this pulley system. In particular, she is concerned that the package will be particular, she is concerned that the package will be too difficult to handle at the top of the ramp and tells too difficult to handle at the top of the ramp and tells you to calculate its acceleration. To determine the you to calculate its acceleration. To determine the influence of friction between the ramp and the influence of friction between the ramp and the package you run some tests. You find that you can package you run some tests. You find that you can push a 50 kg package with a horizontal force of push a 50 kg package with a horizontal force of 250N at a constant speed along a level floor made of 250N at a constant speed along a level floor made of the same material as the ramp. the same material as the ramp.

ProjectProjectBuild the set up below with a block of Build the set up below with a block of

wood (known weight), pulley, string, wood (known weight), pulley, string, and hanging weight.and hanging weight.

Calculate the coefficient of friction Calculate the coefficient of friction between the block of wood and table.between the block of wood and table.

#1

#2

Challenge ProblemsChallenge Problems1.1. What is the coefficient of static What is the coefficient of static

friction between block #1 and the friction between block #1 and the table if the system just begins to table if the system just begins to move? move?

4kg

1kg

#1

#2

Challenge ProblemsChallenge Problems

2.2. Does block #1 move up or down the Does block #1 move up or down the incline?incline?

3.3. What is the acceleration of the What is the acceleration of the system? (assume no friction)system? (assume no friction)

4kg 1kg

#1#2

30°

Challenge ProblemsChallenge Problems

4.4. What is the minimum coefficient of What is the minimum coefficient of static friction needed to prevent the static friction needed to prevent the system from accelerating?system from accelerating?

4kg 1kg

#1#2

30°

Warehouse DesignWarehouse Design

Find the acceleration of the package Find the acceleration of the package as it reaches the worker at the top of as it reaches the worker at the top of the ramp.the ramp.

Does this seem like a safe Does this seem like a safe acceleration or unsafe?acceleration or unsafe?

What else would you like to know What else would you like to know about the situation to determine if it about the situation to determine if it is safe or not? is safe or not?

Lesson #47Lesson #47Topic: Exam 6 ReviewTopic: Exam 6 Review

1/9/07

Assignment: Exam 6 Review due ! Study for Exam 6.

Warm Up: A 10kg block sitting on a table has a string attached to it that hangs off of the edge of the table and connects to a 2kg hanging block. The system moves at constant speed. What is the coefficient of kinetic friction between the 10kg block and the table?


1.1. Practice solving physics problemsPractice solving physics problems

2.2. Complete and check Exam 6 ReviewComplete and check Exam 6 Review

3.3. Plan a tutoring time (if needed)Plan a tutoring time (if needed)

4.4. Complete a bonus problem Complete a bonus problem opportunityopportunity

Warm Up SolutionWarm Up Solution

10kg

2kg

v= constantμk=?

A 10kg block is along side a A 10kg block is along side a 20kg block. An applied force of 20kg block. An applied force of 10N accelerates the system.10N accelerates the system.

25% 25%25%25%1.1. They exert the same They exert the same

force on one another.force on one another.

2.2. The large block The large block exerts a greater force exerts a greater force on the smaller block.on the smaller block.

3.3. The small block The small block exerts a greater force exerts a greater force on the large block.on the large block.

4.4. It depends on the It depends on the acceleration of the acceleration of the system. system.

0 of 5

A 5kg block is at rest on a table when an A 5kg block is at rest on a table when an upward tension force of 10N is applied to it. upward tension force of 10N is applied to it.

The normal force acting on the block is…The normal force acting on the block is… 25% 25%25%25%1.1. 40N40N

2.2. 0N0N

3.3. 60N60N

4.4. 50N50N

0 of 5

An engine accelerates 2 railroad cars along An engine accelerates 2 railroad cars along a track. The tension in the couplings a track. The tension in the couplings

between the cars is …between the cars is …

25% 25%25%25%1.1. Greatest between Greatest between the engine and the the engine and the first carfirst car

2.2. Greatest between Greatest between the second and first the second and first carcar

3.3. The same between The same between both carsboth cars

4.4. Depends on the mass Depends on the mass of the carsof the cars

0of5

A 5kg cable suspends a 50kg crate from the A 5kg cable suspends a 50kg crate from the ceiling. The tension in the cable near the ceiling. The tension in the cable near the

ceiling will be _____ the tension in the cable ceiling will be _____ the tension in the cable near the crate.near the crate.25% 25%25%25%

1.1. Greater thanGreater than

2.2. Less thanLess than

3.3. Equal toEqual to

4.4. Not enough infoNot enough info

0 of 5

Bonus (6pts)Bonus (6pts) Find the minimum Find the minimum andand maximum mass m maximum mass m11 can can

have without accelerating the system. have without accelerating the system. μμss= 0.2= 0.2

5kg m1

#2#1

30°

Bonus 2 (4pts)Bonus 2 (4pts)

Find the maximum height the smaller block Find the maximum height the smaller block reaches. Hint: Find the acceleration of the reaches. Hint: Find the acceleration of the smaller block and calculate it’s “launch” velocity.smaller block and calculate it’s “launch” velocity.

2.2kg

3.2kg

d=1.8m

Documents

Project Pick a partner and build a pulley system with string, weight, and a spring scale. Pick a partner and build a pulley system with string, weight,