Physics M2 Hooke's Law applications -part 1

Physics Module 2 Unit 1

Lessons 8 and 9 BEGIBEGI

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OBJECTIVESOBJECTIVES

TEST YOURSELF!TEST YOURSELF!

Hooke’s Law applications

Use of Elastic Materials



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INTRODUCTIONINTRODUCTION

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Several forces act on a body at any given time.

Do all bodies react to stretching and compression forces in the same manner?

Can you imagine how amazed Robert Hooke would be if he was alive today, to see the numerous applications of his investigation!

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At the end of this slide presentation, you should be able to :Recall Hooke’s LawRecall what is compression, tension and torsionIdentify and explain the numerous applications of Hooke’s Law in the following areas:

Use of elastic materials

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Let’s see how much you can recall about forces!







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Indicate which statement is true and which is false by clicking on TRUE or FALSE. The correct answer will change colour.

TRUE

FALSE

FALSE

FALSE

TRUE

TRUE

TRUE

FALSE

TRUE

FALSE

TRUE

FALSE

MORE FEEDBACK

MORE FEEDBACK







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1. False. Elastic materials when the applied force is removed, DOES returns to its original length, provided that the elastic limit is not exceeded.

2. True. Plastic materials when the applied force is removed, DOES NOT return to its original length.

3. True. deformation is the change in the shape and length of a body when a force is applied.

4. False. Tension is a force that occurs within a body when stretching and compression forces are applied to it.

5. True. torsion is twisting of a material as result of stretching and compression forces.

6. False. Hooke’s law states that the extension is directly proportional to the applied force, provided that the limit of proportionality/elastic limit is not exceeded.







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Shock absorbers – rigid springs attached to each wheel of the vehicle. Compressive forces in the spring counteract the vertical up and down movements of the vehicle, enabling a smooth journey.







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Self – reloading weapons – When the strings of the crossbow is stretched, when released the tension in the string propels the bow forward. A spring pushes another bow upwards into position for firing.







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Self- reloading gun- There is an elaborate arrangement of springs that aid in the high speed propulsion and reloading of bullets.







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Most modern buildings in Japan are constructed with springs at the base to dissipate energy due to earth quake forces.







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This is another design for earthquake proof buildings, where the springs allow the building to move in the direction of the seismic energy and prevent the building from breaking apart as a result of the shaking.







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Compression plates – can used in the transportation of highly flammable and explosive materials to cancel out vertical and lateral movements.







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Anti-vibration dampeners - used to minimize vibration.







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Stockbridge damper - used to minimize vibration of power transmission lines caused by winds or birds.







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Precision Instruments - the ability of the spring to remove to its original length when the applied force is removed ensure the accuracy and reliability of the instrument. For compression testers, spring scale.







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Spring scale – when a person steps onto the scale, the spring is connected to the needle and is moves across the scale. When the person steps off, the spring recoils and the needle go back to the 0 graduation mark.







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Another earthquake –proof design for buildings, where the base of the building is isolated supported on rubber bearings in a moat.







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Some buildings are built where the base of the building is separated from the foundation by being placed on rubber bearings.







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Steel dampening bolts – these are used to prevent vibration and prevent stress to the structure.







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Bumper protectors - to absorb the shock of another car bumping into your vehicle especially when parked in parking lots, where cars get scratched in a bump and run!







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Rubber is a cheap material that is used where machinery made up to different parts are fitted with rubber to dampen vibrations and mechanical noises. This ensure optimal performance of the machinery.







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Urethane is preferred by product designers as it provide longer service life compared to plastics and minimizes noise compared to metals. It is used to make saw blade clamps and jackhammer handle grips, as its anti-vibrational properties help to prevent tendinitis and Carpel tunnel syndrome.







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Are you ready to test yourself? There are five multiple choice items

that you are required to do. For each item, click on the letter of

the correct response and then click the button ‘NEXT QUESTION’ to continue.

Click the ‘BEGIN QUIZ’ button to start doing the quiz.

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BEGIN QUIZ!







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Using the table below, what would be the length of the spring when the load is 70 N?

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A. 8.0 cmA. 8.0 cm

B. 60 cm B. 60 cm

C. 7.25 cmC. 7.25 cm

D. 7.5 cmD. 7.5 cm

FEEDBACKFEEDBACKFEEDBACKFEEDBACK

Load /N 0 20 40 60 80

Length /cm

4.0 5.0 6.0 7.0 8.0







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Using the table below, what would be the length of the spring when the load is 70 N?

A No.B NoC No D Yes The extension is directly proportional to the force, so 70 N will be halfway between 7. 0 and 8.0 cm

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NEXT NEXT QUESTIONQUESTION








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Using the table from question 1, from the results it may be deduced that the extension of the spring is:

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A. Inversely proportional to the load.A. Inversely proportional to the load.

D. Inversely proportional to the square of the load. D. Inversely proportional to the square of the load.

C. Directly proportional to the square of the load. C. Directly proportional to the square of the load.

B. Directly proportional to the load.B. Directly proportional to the load.








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Using the table from question 1, from the results it may be deduced that the extension of the spring is:

A No.B Yes; Hooke’s law states that extension is directly proportional to the load provided that the elastic limit is not exceeded.C No.D No.

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I – section steel beams are preferred to ordinary steel beams because they have :

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A. Lower tensile strength compare to ordinary steel beams.A. Lower tensile strength compare to ordinary steel beams.

D. It bends more easily than ordinary steel beams. D. It bends more easily than ordinary steel beams.

C. It is cheaper than ordinary steel beams.C. It is cheaper than ordinary steel beams.

B. Higher tensile strength compare to ordinary beams.B. Higher tensile strength compare to ordinary beams.








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I – section steel beams are preferred to ordinary steel beams because they have :

A No. B Yes. The top and bottom plate separated by a stringer increases the tensile strength of I beams.

C No. they are more, not significant to answer.D No. the answer is partially correct.

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A semi-automatic pistol can fire several bullets in a short period of time. This is possible because:

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A. It has a magazine that holds up to 14 bullets.A. It has a magazine that holds up to 14 bullets.

D. The bullets are light weight and move very fast.D. The bullets are light weight and move very fast.

C. It uses springs to eject empty cartridges.C. It uses springs to eject empty cartridges.

B. It uses springs to reload and propel bullets.B. It uses springs to reload and propel bullets.








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A semi-automatic pistol can fire several bullets in a short period of time. This is possible because:

A No. the answer is partially right, it does have a magazine holding up to 25 bullets in some pistols.B Yes. When a pistol releases a bullet, a spring at the base of the magazine pushes up another bullet into position.C No; the answer is partially correct.D No; the answer is partially correctly, not relevant to answer.

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Sports utility vehicles are best suited for a comfortable ride to the hilly terrains of the Blue mountains. What feature in the vehicle makes the ride so comfortable?

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B. It is very wide and can drive over most of the potholes . B. It is very wide and can drive over most of the potholes .

D. It has a wide wheel base and does not topple easily. D. It has a wide wheel base and does not topple easily.

C. It has large rubber tires that oppose any upward movement. C. It has large rubber tires that oppose any upward movement.

A. Huge suspension springs attached to each wheel.A. Huge suspension springs attached to each wheel.








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Sports utility vehicles are best suited for a comfortable ride to the hilly terrains of the Blue mountains. What feature in the vehicle makes the ride so comfortable?

A Yes. The springs absorb and cancel any upward acting forces.

B No; the wheel cannot miss every rut on the road surface. C No; rubber can absorbs only some of the upward acting forces.D No. the answer is not relevant to the topic.

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END OF END OF QUIZ QUIZ

END OF END OF QUIZ QUIZ







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You have reached the end of the quiz.

If you wish to review this lesson, go to the first slide.

If you have finished viewing the lesson, click the Close (X) button.

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CoverslideTrusses in roofhttp://t3.gstatic.com/images?q=tbn:ANd9GcSK-qZ9ODjDpNietRHXc1zC9G2Z_E9BP-P3yrzNelCJmHlTguHrBus stophttp://www.edilportale.com/immagini/prodotti-thumb/b_prodotti-50832-rel6de36dae-9971-4838-83ff-4fcb6c0e7605.jpgRubber mountshttp://www.clubchopper.com/photopost/data/500/Rubber_Mounts_25_Brass.jpgSlide 8http://www.techauto.ca/images/Suspension2.jpgSlide 9http://media.midwayusa.com/productimages/880x660/primary/418/418086.jpg







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Slide 10Self reloading gun

http://www.guns.com/wp-content/uploads/2013/05/steyr_diagram.jpg

Slide 11http://www.serviciofilipino.com/pmm/images/article_pic_big.jpg

slide 12 http://scilearn-hscs2012.wikispaces.com/file/view/

3884740118_72e20c0981.jpg/342753974/3884740118_72e20c0981.jpg

Slide http://www.iyrs.edu/Portals/0/Uploads/Images/BlogImages/

Blog2%20142.jpg Slide 17http://i.dailymail.co.uk/i/pix/2008/07/22/article-1037140-

01F2DEBD00000578-174_233x357.jpg







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Compression testerhttp://www.p-wholesale.com/upimg/19/728a1/compression-

tester-ye-2000c-747.jpg

Urethanehttp://www.hellotrade.com/american-urethane-incorporated/saw-

blade-clamps-jackhammer-handle-grips-power-tool-industry.html

Spring scale http://www.google.com.jm/imgres?q=

%27diagram+of+components+of++a+spring+balance%27&num=10&hl=en&biw=1280&bih=666&tbm=isch&tbnid=Qjk32DsBMO5_DM:&imgrefurl=http://www.ehow.com/how-does_4607670_a-scale-work.html&docid=AupmCxRdto_HMM&imgurl=http://img.ehowcdn.

Bumper guardhttp://www.allaround-bumperguards.com/image/

61428939_scaled_416x320.jpg

Physics M2 Hooke's Law applications -part 1

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Transcript of Physics M2 Hooke's Law applications -part 1