University:
High School
Course:
High School Physics
Academic year:

2019
Views:

285

Pages:

14
Author:

Krista Conley

Linear Motion - Picking an Equation Instructions: Read through the following 9 questions. Make а "shopping list" of а/1 the known and unknown values. Decide which equation you would use to solve the proЫem. DO NOT actua/ly solve the proЫem. The first one has been done for you. 1.) А саг increases its speed from 9.6 meters рег second to 11.2 meters per second in 4.0 seconds. The average acceleration of the car during this 4.0-second interval is V; Vf d а t 9.6 m/s 11.2 m/s Лv vf -vi a=--=---t t ? 4.0 s 1 /- L№-(s-1,G,_..... /s ч-s CL ::: b,if,-,./5 :,_ 2;} What is the speed of а 2.5-kilogram mass after it has fallen freely from rest through а distance of 12 meters? 'L Vt d а t v.( ;;;__ .: o,,,..1s V; '2 J ;z V1 о:)_ ,,_ v{ ').__ ::. {'У1 + ·-1,if,..., ls .., v- ·+- '2 u-d ,;2 { - '1. ?;,,.,f !> ::. / 5', :::j_ 1 l =} 3 ;"' 1 s 3.) An astronaut standing on а platform оп the Moon drops а hammer. If the hammer fa/ls 6.0 meters vertically in 2. 7 seconds, what is its acceleration? . V; Vf d а t d o,,..,.,,s , vi'-Ь + Ь,о""" ' b,D ,..,, , о ()-.; J,7 S 1 12м 2 · � 112- Lй)С2 ,75) ! {· 2.. 1 .. (,U' ' rn 1 � 4.) А race саг starting from rest accelerates uniformly at а rate of 4.90 meters per second2 • What is the car's speed after it has traveled 200. meters? V; Vf d а t trf '-:: 0("115 ,Jo о r"' ЧНО ,v"/s VI 1.. vf- ,. - о,;;. '- + L- tL,) i \ ч,qo,.,./s�J.oФ-J l( Forces I i.) Force of Gravity а. Force of gravity (or weight) always acts iп this directioп: .А 1 01J �"',.'-- .. (perpendicu!ar to the surface, against motion, down) Ь. Fiпd the equatioп for the force of gravity (or weight) оп your refereпce tаЫе. Write it here: q' ::: f � () 1"\"s с. Explaiп the differeпce betweeп mass апd weight: (У1 tU)/.J �4 И)УХJ h..-J- �� ,_,.,,k.rc_ d. Suppose you have а 15 kg object. i. Calculate its weight оп Earth. J � -1;? 1.лi,� j,.;f Fj :: /'171\/ -1,'3,П'I{ - 2 ii. If the acceleratioп due to gravity оп the mооп is 1.6 m/s , calculate its weight оп the mооп. /,&-""/s iii. .,__ J:_J ,fY' --- Is ,_ FJ "' / 'Jl,e,.3 If the acceleratioп due to gravity оп Mars is 3.7 m/s2, determiпe its � -оп Mars. s+, л 157cJ е. Calculate the weight of а 20 g object оп Earth. '-д, o;;io '\� ,;:, -Cf ,�/ ,--,--.fs 2.) Normal f'orce а. 'Normal Force always acts iп this directioп: [!J� � ---. d-<--C,v_R--c'-'� (perpendicu!ar to the surface, ag.зinst motion, down) Ь. Draw where the пormal force is acting in the following diagram. Determine tl1e magnitude of the normal force. А1 !"" ;;, j V - � j\ � S• - - 2k r fj� _ !а/,ь/V 1 ,, ., ' r1'--_,v : Draw where the normal force is acting iп the followiпg diagram. Determiпe the magnitude of the normal rce. Hint: Identify all of t'1,� �r' ' ? Applied Force = 10 N the forces actiпg in г---' +-�-=з�о•�� the y-direction ! 2 kg Fн = fЧ, 1,,1.J JC::1, b.AI З.) Frictional Force а. Frictional Force always acts in this direction: (perpendicutar to Ь. What is the difference between kinetic and static coefficients of friction: . �,1 (,� ,'У' a-h'w-- r > . \ с5тг,,,/fc:j ) :-, ' ; 6-,v,' ,..,-,z. ;: (, (,,,, ь 7 1 F д° L ' ) Г'l- ( () "" (_ f .,t ::- /,,, (,, 7-J. /(]· l i' (',1(1.И<,,(. r 17 ·'2- • /V с. А person weighs 600 N оп the surface of planet Earth. What is the weight of the person if they move to а distance 1 radii away from the surface of Earth? i, First think. lt- { 1 "\ ,;l.f М D"_г ) How has the distance changed? 1 . Should the force increase or decrease? -��---·,./,,, Ву what factor should the force change? , svлJ �ijAV(_, 2.)Electrical Force а. TRUE/FALSE Electrical force сап Ье attractive or repulsive. __,...;-..L�--Ь. Calculate the electrical force between two protons located 2 х 10-5 meters apart. Is the force attractive or repulsive? Fe " f::_ 3 й ,_ t /19 х ю 'i - 0 .I\J ,,, 2, /с ,_ С ( {,;<. /,г ,9 с_);.<..2- 5". 7 �->'-- I О·-' 7 Л/ с. How does the magnitude of the force calculated in Ь.) change if the protons are brought to а distance of 1 х 10·5 meters apart from each other? i. First think. _, { lf Z- . ;,.;J ""' "<-<Л'. i How has the distance changed? � \ll .1.'1 Should the force increase or decrease? ------Ву what factor should the force change? х 'i 1 ()...,� З.}Centripetal Force - Center seeking! а. Label the centripetal acceleration, centripetal force, and tangential velocity in the following diagram of а car trave/ing around а circle with radius 2.5 meters. �:� 2.5m -.../ ,f. )/' t:e.1.. �ucfent Ь. Calculate the distance traveled (or the circumference!) of the car as it goes around the circle. с. Calculate how fast the car is traveling if it takes 4 seconds to travel around the circle once. э., с1,,.., I5 'f 5 d. Calculate the centripetal acceleration of the car. г {_3 , q,,,.,( 5 ) е. Calculate the centripetal force of the 2000 kg car. Fc ' fY1- о:_ с. , ;),, !) v о V с;с ь r ~I ' ,_ � i ;;_ / ,2.,, 0 л/ 4.}Free-body Diagram (FBD} Now that we've looked at all the forces individually, let's look at them а/1 together! Label а/1 forces acting in each of the following situations: taЫe • а. А Ьа/1 freely-falling Ь. А book s �f' � с. А sign hanging from two wires i11,,f3 1 Fr, r'---'--i Yj d. An object being dragged F,,,v F+ __ --1,,--, ,4-,,J---.i.---1-.,,, 1-:::А. е. А саг traveling at constant velocity Ff'. " f-iv -�? р- f. Two protons ,с, �·, у:._ � р .(. 5.)Net Force а. Find the equation for the net force acting оп ап object оп your reference tаЫе. Write it here: d1;..tvG<-AI '-h,"ГЬг_ а..;:. . Fт,_d- h-ut " � Ь. А 5 kg ball is kicked with а force of 20 N. What is the magnitude of .the ball's acceleration? CL "'. _?-?IV :. б .L s-ь Ч,..,... / с. Calculate the net force acting оп ап object in the following situations: i. The object is stationary ii. The object is pulled at а constant velocity . o·z h-,,A iii. The object is pulled with а 10 N force across а horizontal frictionless surface iv. The object is pulled with а 10 N force across а horizontal surface with а frictional force of 4 N. • d. If the object is question с.) has а mass of 2 kg, calculate the acceleration for each situation. А и i. ii. с! е. А З kg Ыосk is being pulled across а level horizontal surface with а force of 80 Newtons. The Ыосk accelerates at а rate of 15 m/s2 • What is the frictional force acting between the Ыосk and the surface? 2. °'-" Fn.d- ·� � Lfgv.} Ff � 35,-у/ • ____ /1.t:4 Horizontal ProJ·ectiles . V - .ftA4 f.: i?- v.�•. <А �-<'Ni , . . / \V Projectiles move in two dimensions. Therefore, when we analyze the motion of а projectile, we break the motion up into its horizontal and vertical parts, ог components. 1.) Check out the picture to the right: а) Mark an "х" оп the diagram representing the point where the саг сап first Ье considered а "projectile." Ь) Draw an arrow starting а! point А, showing the horizontal component of the car's motion. Label it "vx." с) Draw ап arrow starting а! point А, showing the vertical component of the car's motion. Label it "vy." d) After the саг becomes airborne, what controls the magnitude of its HORIZONTAL SPEED? ; f1 i-h 'a.,L v vl о ел"&; -� at f.{° е) After the саг becomes airborne, what controls the magnitude of its VERTICAL SPEED? • ''._/, �J f) As the саг moves from point А to point В, what happens !о the magnitude of the car's horizontal velocity component? 11 д� g) As the саг moves from point А to point В, what happens to the magnitude of the car's vertical velocity component? jп �<'КА h) Two students аге arguing. ВоЬЬу says the саг is accelerating, but only in the horizontal direction. Carly agrees that the саг is accelerating, but only in the vertical direction. Who, if апуопе, is correct? Why? � ,м '1v vtt./9-, C-d.. '½:! lf the саг is projected horizontally off of the cliff at а s� 30 m/s ... i) What is the initial horizontal speed of the саг? j) What is the initial vertical speed of the саг? ��:J ch·,,: c:h ,м... � Ьh-vr:#: -, � rл -f1-;:_ Use the following information to answer questions 2 and 3. 1/1 'Or-1s v.f, Projectile А is launched horizontally at а speed of 15 m/s from the top of а cliff and strikes а level surface below 3 seconds later. Projectile В is launched horizontally from the same location at а speed of 30 m/ s. [neglect friction] ,,_, ·'1,'6,-,.,/s' 2.) Approximately how high is the cliff? 7 35 d. ." 7 (1)29m @4m -ь (3)60m • (4)104m d._ ;О V1 � 1 '\, ..:.f " 3.) Compared to the time it takes projectile А to reach the ground, the time it takes projectile В to reach the ground is (11\'ithe same 'izrtwice as great (3) half as great (4) four times as great ____ д t' 4.) The diagram to the right represents the path of а stunt саг that is driven off а cliff, neglecting friction. ✓ Pathofcar : Compared to the horizontal component of the car's velocity at point А, the horizontal component of the car's velocity at point В is ...... ...... � 1 1 '- 1 1 1 1 1 1 (1) smaller � greater ®the same оm 1 1 1 1 10. m ', \ \ \ \ • • . 20. m 5.) А 2 kg ball rolls with а horizontal velocity of 1О m/s off of а 1.5 meter high tаЫе. Determine the horizontal range of the mагЫе as it falls to the floor. vt,1д,.,_(s. ,L,? .,,1, 10,�,/s tf--' O ,,,,,�.,, d 0 ? /О,.,,("!;;, и -io v·I, r ,, " о t 1 11.. < -1 '1)·t t'- •7 d г v Ja v1./-•t't1....,t "- "'' ·"i ii; 1,5',_, t-� 2 " .J ·t /o,,_/s "' .А. (),5,S {),ЪJj 6.) А ball player wishes to determine her pitching speed Ьу throwing а ball horizontally from an elevation of 4.0 m above the ground. She sees the ball land 25.m down range . Determine the speed of the ball as it leaves her hand. и·" ? 1/1 =0.-\� v.f -- d � '1 ,D,~ 11-_ ::-'1,'6-1 s' t- � V • .J 7 1.(.и ""' д/i.os )C,r") � '1 i-C -1 � ./;,о,405 7,,,)""1 (),'/05 ./с :: 2. '3 ·=/..5 • • !.,,<.S' • Angled Projectiles'\ V(,{.,(И:,� J "'"' ;z ��-v.A 5" А kicked soccer Ьа/1 has ап initial velocity of25 meters per second at ап ang!e of 30 ° above the horizontal, level ground. [Neglect friction.J 1.) Calculate the magnitude of the vertical component of the ball's initial velocity. v,' if /J,., ,(Y> / 5 = StA,(зo)·z<;-rs::: 2.) What is the acceleration in the vertical direction? - '1, 'ь",,-,л / 5 2 v�·.,, 12 �>l5 . 3.) What happens to the magnitude of the ball's vertical velocity as the ball travels upwards v- j 0 () d'" 7 Ck (f to its peak? ,(',r-UvrJ.иJ � Оr,, /5 '5,.:f �,..,L. •· tL:. - �,'if,,./, 4.) What is the magnitude of the ball's vertical velocity at its peak? () /V'I I � ·t � 7 ,.,, 5.) What happens to the magnitude of the ball's vertical velocity as the ball travels back downwards? lлLn;,,ci,lk,J 6.) How do we symbolize that the ball's direction has changed in the vertical direction? ·+.J 7.) Calculate the amount of time it takes the ball to get to its highest point. tt.= -1,'if,,,...Js /... = CJ,.,,.Js- JZ/:1~,,_,1f v+-� -t ½;--8.) Calculate the maximum height the ball reaches above its initial position. d :.· V\;.j.. -t I /1-- cct .,_ - )J.i_i{,f.3s) 1- 111- (-'J,'fi,.,-/f·,-){, /-3s)·,_ ,:: /1,,.;;5 - t,z'i5 -=-(8/VI} ,.,._/$ 9.) Calculate the magnitude ofthe horizontal component of the ball's initial velocity. vi' х :: и 5 l э о) 7,,5�.,,., / 1 , :г 1, 7 rn I s 0_· ,_,,,._!_5_·_ 10.) What is the acceleration in the horizontal direction? __ -siмp 11.) What happens to the magnitude of the ball's horizontal velocity as the ball travels • upwards to its peak? h!YJAbvf: 12.) What is the magnitude of the ball's horizontal velocity at its peak? .: / ,7,.,,.., 15 13.) What happens to the magnitude of the ball's horizontal velocity as the ball travels back downwards? [лvl.41h-,.;f бhf 14.) Calculate the total amount of time the ball is in the air. • 15.) Calculate the horizontal distance the ball travels. v:: df -;, 1,.,-i,; 2 J_ �.,s 16.) On the diagram, sketch the path of the ball's flight from its initial position at point Puntll it returns to level ground. ,, " r ' 7 7 7 7 7 7 7 7 7 7 7 7 Level ground 17.) On the diagram below, sketch the path of treball'sili§ht from its initial position at poiпt Р until it returпs to level gro;ioo, ifthe projectile was now launched at 45° instead of only 30 ° . '"' \ / 7 j7 7 7 7 7 7 7 7 7 7 / 7 7 Level ground \ 18.) On the diagram below, sketch the path of the ball's flight from its initial position at poiпt Puntil it returпs to level grouпd, still at 30 °, but поw iпcluding frictioп. � / f -" " 7 7 7 7 7 7 7 7 7 )- 7 7 Level ground •