SPRIN9S -POTENTIAL ENERGY and.

Transcription

1 ( '" ". ) (Ba.5i~ ) p?~ ~. i '" '""..: r ;'"'j" " SPRIN9S -POTENTIAL ENERGY and... SIMPLE HARMONIC ry1tion 1) \Vhat are t.'1.etwo equations that des9ribe -How mu.ch a spring st:retches at compresses when ", " pushed or pulledan, ',,1~Nf~~"" r. rfl~,.. 1,. :' '", - The potential energy stored in a.stretched:spring. - (Makesure you'understandk value for springs) i<,.. 2) The spring shawl). has a constant K =4 N/rn. A 1kg mass is hung 11this spring FIND-. the stretchintl:1espring,the PE storedinthe spring., j/ III III I r( I, f {2-6 flj ' ','

2 . " 3) Make two quick graphs for the spring in question 2 ift~.f(:;liowlo.gd.ass.es ~e placed on it. Notethe characteristics ofthe graphs.-" ' '".... '... fi\ 'v'/','..i-,f e.1 ~ "" ~ ' - '.'.. PC:..a////~~.~ J.:'...., tj \.(".:; t..joo;/" \ '. Y"'\ p~ k " " ) -.,. "... ". : 'j,. '1..I. B,Hr(J<.~ I (ft're}<. '-. ~).::.-... ".. 'i:t:.,,' I,,--,-_c"""-'-'.,,! '.,.. "...,..., '.. '" '"'' ' I, 1--~--~,_..(--'t-c:r:! "':'":''':''':''''''' ~_..:_..~._.+~ _.j"-'f'-"+"'~-'+-"+-'i'" ". i''';''':'',. I '".,,..~,.,1...il. (51~)

3 '" I.J u.. j il.. '-' V I C ''''l.7 1-:) 2 A 2.-newtQn weight is attached to a spring, causing it to stretch, as shown ill the diagram b',!ow. ~-i~i--:r ~. What is the spring constant of this spring? (1).5 N(m' (3) 2. Nlm (2).25 N/m (4) 4. Nlm 18 A spring has a spring constant,of 12 newtons i) per meter. How much potential energy is stored in the spring as it is stretched.2 meter? (1) 2.4 J (3) 12 J (2) 4.8J (4) 24J J) 21 :,i'ring..a has a spring constant of 14 newtons per meter, and spring B has a spring constant of 28 newtons' pet meter. Both springs are stretched the same distance. Compared to the potential energy stored in spring A, the potential energy stored in spring B is J. the same 3 half as great 2 twice as great 4 four times as great w 2 Which graph best represents the relationship be. tween the elongation ~~ of an ideal spring and the applied force? t= E S g!1 9 w 9 '" FORCE ;ORCE LL ~ < ':;:!1 s:! a oj m ;""CE!'ORCE (1) (2) (3) (4)

4 II~ In the diagrambelow, a. student compresses the' ~ spring in ;. pop-up toy O.~2meter..,.,..p, t.f ', (1) If the spring has a spring constant of 34 newtons per me~~r,how much energy is being stored in the spring? '.68 J (3) 3.4 J (2).14J (4) 6.8,J- ([J Which graph best represents the elastic poten- ':::', tial energy stored in a spring (PEJ as a function :~,:':' of its elongation, x? PEs.',,,',' '..;.,..PESI~..x x ( 1 ) ( 3 ) PEs PEs x ( 2 ) ( 4 ) x,i' ~i, The unstretched spring in the diagram belowhas V a length of.4 meter and spring constant k. A weight is hung from the spring, causing it to stretch to a length of.6 meter. Unstretched Stretched!~~~Ii<!f~W;\;;, p;~~ (:':=-~..2 ~. ~J:m ~.6 1 ='). m ~ How many joules of elastic potential energy are stored in this stretched spring? (1).2 X k (3).18>~k (2).8 X k (4) 2. X k

5 ',,,".. - '''',,,,,, M ~spring isstr,etched,its elasticpoten~,(i) decreases " -," (2) 'increases (3) rei,il,iunsthe' s~e energy fj ;5 J 1 A catapult with a spring constant of 1. x 14newtons per meter is required to launch an airplane from the deck of an aircraft carrier. The plane is ' released when it has been 'displaced.5 meter from its equilibrium position by the catapult. The energy,acquil"ed,by the ~lane from the catapult d~g takeoff is approximately (1).1.3x 13J (3) 2.5x 13J (2) 2. x 14J. (4) 1. x 14J. it The' graph below.represents the relationship between the forc~ app4ed to a spring and the compression (displacement) of the spring. AppliedForce vs. Compression 1..._~--.9!) The graph below shows the relationship between the elongation of a spring and the force applied to the spring causing it to stretch. \;Y~at is the spring constant for this?pring? (1) 1. N/m (3).2 N/m (2) 2.5 N/m (4).4 N/m Elongation vs. Applied Force.6 E.5 ~.4 ~.3 ~.2 ED O.i Force (N) vvhat is the spring consbmt for this spring? (1).2 N/m (~)) 25 N/rn (2.) 2. N/m (4) 5. N/m

6 , i ~ ,,'."" ", f1 BaSeyour ansv,ersto q~estions.6'6and'67 oiithe informatiq~b~low~d. on yoci-~ow~~dg~'~f7'~)'s~cs., Usinga spring toy like the one shownin the diagrain, a physics'teiwher pushes' on the'toy,,, compressing the' spring, causing the suction cup to stick to the base of the toy.., ",' ' Trials1-5 TriciJ.!6 ' Not separated from base Separated, from base' Suction cup, ~.. Spring: ~Base ~ When'the teacher removes her hand, the toy pops straight up and just brushes against the ceiling. She does this demonstration five times, always Vv'iththe same result. vvhen the teacher repeats the demonstration for the.sixth time the toy crashes agaj.nst the. ceiling vvithconsiderable force. The students notice that in ~is trial, the spring and toy separated from the base at the moment the spring released. The teacher puts the toy back together, repeats the demonstration just brushes against the. ceiling. and the toy once agair:.66 Describe the conversions that take place between pairs of the three forms of mechanical energy, beginning 'v'\liththe work done by the teacher on the toy and ending with the formes) of energy possessed by the toy as it hits the ceiling. [Neglect friction.] [3], 67 Explain, in terms of mass and' energy, why the spring toy hits the ceiling in the si1.1:htrial and not in the other trials. [2]