, Chapter 3 Accelerated Motion 5) In the formula'; = vo 2 + 2ax, what does x represent? Name _ Answer: The CHANGE in POSITION, which is NOT necessarily the distance gone. Oiff:2 11) Refer to the figure: +5 V (mlS} o 8 10 t (5) -5 Based on all the graphical information A) C and 0 meet at the same position at t = 8 s. GA lJ'r Tl:LL Ft24JfYL B) C and 0 will meet at the same position at t = 10 S. CAN / , riEL/.. C) C and 0 will never meet at the same position. CItN' TeLL not enough information is given to decide if an mee. y C!S E) t e acce eration 0 IS nega Ive. I r I J PO.J I Tt VI! - Answer: 0 Oiff:2 15) Consider the average velocity of an object equal to its instantaneous velocity. A) This is never true. /JO. B) This is the case o~ when the velocity is increasing at a constant rate. IJO - C) This is always true. ~ o. 0) This is the case ONLY when the velocity is constant. ~or 4LWA-'(J E) This can be true at certain instants. 'I~S Answer: E Oiff:2
Transcript
, Chapter 3 Accelerated Motion
5) In the formula'; = vo2 + 2ax, what does x represent?
Name _
Answer: The CHANGE in POSITION, which is NOT necessarily the distance gone.Oiff:2
11) Refer to the figure:
+5V
(mlS}
o 8 10t (5)
-5
Based on all the graphical informationA) C and 0 meet at the same position at t = 8 s. GA lJ'r Tl:LL Ft24JfYLB) C and 0 will meet at the same position at t = 10 S. CAN/, riEL/..C) C and 0 will never meet at the same position. CItN' TeLL
not enough information is given to decide if an mee. y C!SE) t e acce eration 0 IS nega Ive. I r I J PO.J I Tt VI! -
Answer: 0Oiff:2
15) Consider the average velocity of an object equal to its instantaneous velocity.A) This is never true. /JO.B) This is the case o~ when the velocity is increasing at a constant rate. IJO -C) This is always true. ~ o.0) This is the case ONLY when the velocity is constant. ~or 4LWA-'(JE) This can be true at certain instants. 'I~S
Answer: EOiff:2
12) Refer to the figure:
+5V
(mls}
o 8 10t (5)
-5During the first 8 s SOY -2. "I.
;A.TC ana 0 are both slowing down. TUt ~ H.()iY1 -+ <; "I~ f'eI+l "'k (l~ - I'> to :.'an have cons an vefO"Clties. UL
C) C has the same average velocity as D. SAIk( SP(,iE 0 - "l.Lf Olf"rl!"4.C/lJ( JJ,tfc..no/l5..D) C is slowing down, and 0 isspeeding up. ~TI1 SU;()JI/IIe,E) the acceleration of 0 is negative. ~~J/nvf
Answer: ADiff: 2
18) Which graph represents a constant non-zero_velocity?
al V (f)'tS. rf;tJr r:; Vel-- l~(t{) L el__VeL:=--
~UJp~(8) gra~'yC) grapn cD) graph dE) both graphs a and d
Answer: BDiff:2
Oiff:3
Answer: (a) 22.4 min(b) -0.87 m/s2
, ',,,',rnl'"1) All of the following are scalars, except
A) mass.
~norctD D IR. (c. fli.! Y\. M..A-lT'Cfl.:S,emperature.
0) distance.E) income.
Answer: BOiff:1
2) A car was moving 110. km/hour. (30.6 m/s) 7Ji:= 36. 6 ~(a) How long did it take to go 41,038m? Al''' '11 tloSll", 4t :=~-(b) If it stopped in 35. s, what was its average acceferation (m/s2) as ~ slowed down?
1J~cIt
ev=Jt - =!. - I( '/J'd ••
- V - '0.6 "Y~
3) It is possible to have constant speed, but still be accelerating. _ L\V ~sp~e.d(J~ dt~LCUc.d €..VC{ f0Y\. 4 /;; c"'1.
Answer: TRUE (if you are moving in a CIRCLE - your direction would be changing)Oiff:2
4) It is possible to have zero acceleration, and still be moving.
Answer: TRUE (moving at constant velocity)Oiff:2 ----------
5) Which graph(s represent(s) zero acceleration?
~I-- ~ 1====_-_- t
C) VIll-=:::::
) band cB a and ~C) c and'd0) only aE) only b
Answer: BOiff: 2
V
e~
Answer: FALSE (It would be a positive acceleration.)Oiff:2 -
6) A negative velocity, approaching zero, represents a negative acceleration.
o-~"'"'- +,-.
1SLOpe = (Jor., nll"rr.7) The graph plots the velocity of two cars (A and B) along the same straight road.
CARB
~O~I 'h""", V"dO'I'I-~t
v
Which car reverses direction?A
Answer: BOiff: 2
9) Explain how a POSITIVE acceleration could slow an object down98.::: ~
Answer: An object which was moving in the negative direction would slow down if its accelerationwere positive (a negative acceleration would mean the velocity was getting more negative: it would bespeeding up in the negative direction).Oiff: 2
10) If an object is accelerating, it must therefore undergoA) a de.cre.a . velocit. i\\ 'A.'j &! ,~~ a change in velocity.
an increase in velocil. 'A'18(0) a change in direction. lV\.l\'f.e,CE) a change in speed. MirY8c.
Answer: B (It MAY do A, C, 0, or E, but it MUST do B)Oiff:2
Vi =-0 MphVr~ b{)"'P~L\t: 8~
11) A new car manufacturer advertises that their car can go "from zero to sixty in 8 S." This is adescription of
A) instantaneous speed.S) average speed.C . ation.D) average acceleration.
Answer: 0Diff: 2
12) Refer to the figure:
+5V
(mls)
o 8 10t (s)
-5
During the first 8 sA) 0 always has a greater acceleration than C. {\J (J IS as a reater acceleration than D. N 6 v I Iv to('C their accelerations are e ua In magnltu e, u OSI g. () I tL(!(..n ~11)
D) their acce era Ions are equal in magnl u e, an eq n. Or ff:(;2.EJvr P//ltLfU)l-.E) 0 is speeding up while C is slowing down ~ont,S.(J)WIt\4 . r
Answer: CDiff:2
Kinematic Equations (Constant Acceleration)
2) Eric watches a jet powered truck during an "air-show." It accelerates from rest to 134 mls in8.0 seconds. What is the acceleration? Difficult: The acceleration was equivalent to how many
4) Consider a mass initially moving at 7.50 m/s. -V l = 7.r-()MI.t 7.J { ,,? 4 t.-~ ~ '"(J,rr~,..1t~(a) How long does it take to move 3.5 km if it accelerates at 0.550 m/s2).? 4 ¥__ ~ ,..• J ,S.t", t j,1~_(b) How fast is it moving after this acceleration? l.,
6) A bullet moving at 244. mls strikes a tree and penetrates a distance of 8.34 mm before stopping.What was the average acceleration of the bullet as it slowed? DJ<:.-8.?'f '" M. •• 8.3~NO -jJII. v,:..:. 2 '('{lj
z-&~ = G7) Which graph represents constant positive acceleration?
a) b)
Vol---I q«.:-O
d)
A) graph aB) graph b
ra h cr
E both graphs c and d
Answer: 0Diff:2
8) A car traveling 16.7m/s accelerates at the rate of 4.0 m/s2. How much time is required for the car toreach a speed of 25.0 m/s? 7.J:: (",7 "'IJ. Cl:: Lf,0 /fit -:. D.t..7 11f :~'. 0"6
lJ, = 1)~t q 4t ::; 2.:[.0 '''Ii - Ib.7,,;' t. . ]A~swer:2.1s lft-V:':Ol\tJ '(,0 "'/,L C 2,/.sDlff:2 :::'+c'--"O ~ : d t.9) An auto accelerates from 7.0 mls at 0.71 m/s2. It travels a distance of 1.033km while accelerating.
(a) What is the final speed at the end of that displacement? V. :070'" .:(" ()7/ f'/./(b) How many seconds did it take to accelerate from 7.0 m/s? I • U • /5 ~
10) Can an object's velocity chan e direction w . acceleration' tant? ~es, t IS IS possible and_a rock thrown strai ht u is an exampl. Q:= - q.8.f? 11c.~"'Ao l!0, this IS no possible because it is a ys speeding up. '-HJ ,J ':!
C) Yes, this is possible, and a car that starts from rest, speeds up, slows to a stop, and thenbacks up is an example. NO. c£> c'ad ••vv...tUlr-. *IN.,,, \\.~'lh'v'{".0) No, this is not possible because it is always speeding up or always slowing down, but it cannever tum around. N (),
Answer: AOiff:2
11) An airplane increases its speed from 100.0 mls to 160 mIs, at the average rate of 15 m/s2. Howmuch time does it take for the complete increase in speed? \) ~ :- \O()"'~ -U ~••.I(,o1J c:: Ir%'l
~:~~ ~- 7B s b,v.)0.0577s u~::;1)~tc<L\t
0)17.3sE)8.0s Vt-V~=C{.£\t
"Vf -1J~~ CIt- Cl '
I ~O"'I~- lOO.~~LJ(<.-. "6'- - 1.O~
12) A car traveling 20.0 mls is able to stop in a distance d. Assuming e same braking force, whatdistance does this car require to stop when it is traveling twice as fast? 1)' :- 2.() "'/ ••••J LJ/l
A)d '- I. -V '. 1.. '1 J Vu. '=<7'-0'1&B) 2 d 1).( ~ V: ' r L-fJ V::\J) ~, I.. Itt.. () f, :() HI ""._' It'd ' 2.0- IJ v,.~0 uCO)4-fi
dd -0/- V•.'- '"2-1(4d\ ' 'V 1_V.L 'i,""'(z.
? '1 I, "
2 2d Vt~V, " 44 J Jq ~o"lt:il
2C( -t:: ,~-: ('J. "1 )' Lj (Answer: D (Slow Dow[1! It takes four time the dista'nce to s tp if you doullie r speed. Isn'tthat what your drivel'S ed teacher tatlgnfYou?)Diff: 2
13) A jet fighter plane is launched from a catapult on "an aircraft carrier. It reaches a speed of 42 mlsat the end of the catapult, and this requires 2,0 s. Assuming the acceleration is constant, what is the
length ~f)t~~~atapult? 1)l :'0 ,.•../~ 1),:: '-('Z [IA IJ 4t;-2.0 S L~?C = 7
rsmsni 1)(. .•..0. t q~t)~)~ci~ l 4 '1.-:: iJ.:,tL) j- { q@£J2v~'-V.; •. ~ b. tE) 84m ll~-o.. 4A'-~~Vs).j~~/'''£12sJl
Answer: B ~ ~ q L'Z. Jo iff: 2 ~
'i2"lJ 'O'~ _2/ ~I ~2,0j - /fJ
15) An astronaut on a strange new planet finds that she can jump up to a maximum height of27.meters when her initial upward speed is 6.0 m/s. What is the magnitude of the acceleration ofgravity on the planet? (hint: find a. but it isn't 9.80m/s2 - that is on Earth at sea level.)
A,v.. :.2.7"'- Vi : ~.O'"( ~ ~? -,1 0 0 "/~ 0,,& ••• I .•...@jAnswer: 0.67 m/s2 ~ j, ,vf I; Ij . a G1"/Diff: 2 lJ '\ ""J" ~ i"" A r lJ •. -0:1 '" 2...4.:1 2. 27w~ ' If-
f U, t-Q ".:1 "U.i~ittt:a..18) Can an object have increasing speed while its acceleration 1~~ecreasJng?
A) No, this is impossible because of the way in which acceleration is defined.B) Yes and an example would be an object falling in the absence of air friction.C) No if accele.r.at"on is decreasin the bjecLwilLbe.slowing..dQ
es and an example would be an object released from rest in the presence of air friction
Answer: 0o iff: 2
20) A ball is released moving straight up at 15. m/s. At some time later it is falling downward at15.m/s. What was the magnitude of its average velocity over this time periocj? -Vc: ~ (r ""(.
~~m/s) -::=:::: (. m/s IJ( ~-ICYr
C) 15. m/sD) 7.5 m/sE) 22. m/s
Answer: A (Note: velocity has a direction!)Diff: 2 .
-Of -"Vc'-- ~tlC4
,1,~a)((0 7 ~ "'(/'tl
12"i:~(}, d 6 na.l\::: t ]
R,o~ X(o'~~\(~"""!J.L\-.6~!k b()~;')L; 'f"'0 :
~~01
21) A bullet moving horizontally with a speed of 500.0 m/s strikes a sandbag and penetrates adistance of 10.0 em. "V ::.- I~"\ 1\\1 t\ 'V"" 10 - 0 '00
(a) What is the average acceleration of the bullet? ''OW'" '-\,. , ••.• - , I, .,(b) How long does it take to come to rest? 4:~ lit: ? 1.)( =: 'Dc2 T 2(;~J
. (b) 0.400 ms V. l.1il U -1): .,. I( 4 C'J ~ "Is .SM --.Dlff' 3 ~ , t' -- _. 1= t.tYI'I~. 2(A~ ::-(J 'iJ -1) • 4t. -,.2,Nc)~1!~~_27) Captain Rickard orders his starship to accelerate from rest a "1g" (accel = 9.8 m/s2). How longdoes it take the starship to reach one-tenth the speed of light if light travels 3.00 x 108m/s?
q ~ 7.S ~6.... 11i=0 '"6 () J ~ S,(JOX,06 11k "!.I "Answer: 35. days 1 I~'i6 c "I, t -;'1) ~ 1 q ijt)Diff:2
28) A car with good tires on a dry road can slow at about 5.0 m/s2 when braking. If the car is travelingat 89. kmlh (24.7 m/s):
(a) how long does it take the car to stop under these conditions?(b) how far does the car travel during this time?
Answer: (a) 4.9 s(b) 62 m
Diff:3
CARA
CAR8
During the time interval shown, which car is AHEAD?A) Car A)-earB
C) insufficient information
Answer: CDiff: 2
34) Under what condition is average velocity equal to the average of the object's initial and finalvelocity? lI ••.lou.'~~ If~1-. ~
A) This can only occur if there is no acceleration. ( ...J • I ",'
l3()-fhe acceleration must e constant. It- S""</';.5 U f,''''<:...C]rtre acceleration mus 5e Cons antly changing. ~0) This can occur only when they are zero.
Answer: BDiff:2
36) Which graph represents an object at rest?
~I:::::::===- -0=0 b)
c) Xe~ ""\Joe>[
~~:~C) graph c0) graph dE) both graphs a and d
Answer: AOiff: 2
d) ~LLI7
Free Fall
Answer: COiff: 2
39) A bullet moving at 244. m/s strikes a tree and penetrates a distance of 8.34 mm before stopping.Assuming a constant acceleration, how long did it take the bullet to stop? 1) ~-0:. 1"v~~tj, d -LelV"a
. ~ ":~ ~.S~ (S-, 'i .J...,L? ~ 1'/(1' S..(k)\) ::4) When a ball IS thrown stralg~ up, the ac~ ler~d~ at I s highest POlnt"1
A) u"pward.B(down~C) zero.0) horizontal.E) minimum.
Answer: BOiff:2
7) The "acceleration of gravity" is 9.8 m/s2 everywhere on the surface of the Earth ..--_===~------Answer: FALSE (It varies depending on the Earth below.) .Oiff: 1
8) A skydiver jumps from a high-flying plane. When she reaches terminal velocity. her velocityA) is increasing at a constant rate.B) is decreasing.C . .
O) A ball is thrown straight up with an initial speed of 36 m/s. How lon~ Soes it take to return to its-I' tarting point? -" .• ") 1 J "I • =o -- V\~;)b.> IJ.,v' ~ ~~:yO"" 4: -?-8t>ldt 4~:oV"4t fiaa~.l
'~A~swe~econds? () ~ ..,\. AJ .!. ;t; j1..J -V; ~ J «IJ..CJCl01ff: 2 Vl U. \,. "1 ~ C( @ C z. l{J
11) "Big Mike" throws a baseball straight up and it eventually falls back to him. When the bal was al _its highest point, what was its velocity and what was its acceleration? (remember to includemagnitude and direction)
Answer: Velocity was zero, acceleration was 9.8 m/s2 downward.Diff:2 -~
12) An object moving under the influence of only gravity is said to be in _ __
Answer: free fallDiff:1
13) A ball is thrown straight up and returns to its starting point in 8.0 seconds under an accelerationdue to gravity. Which of the following is true? 4 t.;. 0 tJ
A) It took less time to rise than to fall. t/. ~B) T.co are rise and fall ti es we e to know the mass of the ball. C( _ -4 e-. I til.g It took the m~tlme to rise as it took to fall. (.'1 4> . t.(.IO/'2.DTlrtook-lenge to-rise-than-tO"fall. '19; ~ 1)
!' /lAnswer: C C7Diff:2
14) Contrast Aristotle's predictions concerning free-falling bodies with Galileo's predictions.
Answer: Aristotle said heavier bodies fall faster than light bodies; so if the two were dropped at thesame time, the heavier body would strike the ground sooner. Galileo observed that the motion wasindependent of the body's mass provided air friction was not significant.Diff: 2
15) When an object is released from rest and falls in the absence of friction, which of the following istrue concerning its motion?
A) Its velocity is constant. ~ aLl.de~1~B) The acceleration increases at a constant rate. Nd Co"-shl\.t ~,-e. (~f/CJ't.C) Both its acceleration and its velocity are constant. No '""1.1••.• 'N. J. ~ •• A
j . celeration . s velocity is constant. N 0 '.::J C 'vw.,;y c.~.E) Its acceleratio is consta 11lUC' ( .,
Answer: EDiff:1
17) Consider a heavy object which is thrown straight up, reaches its highest point, and then falls backdown to the ground. During what parts of the trajectory was it in "FREEFALL"? (assume here that airfriction is negligible)
Answer: During its ntire travel d ring which gravity was the only significant influence on it (it "freelyfell" moving up, movi own, and at its motionless highest point).Diff: 2
19) A can, after having been given a kick, moves up along a smooth hill of ice. It willA) have a varying acceleration along the hill.B) have the same acceleration, both up the hill and down the hill.C) have a constant acceleration up the hill, but a different constant acceleration when it comesback down the hill.D) travel at constant velocity.
Answer: BDiff:2
16) Which physical unit is a fps acceleration?A) -120 milsB)40 km,SWC) 9.8 m/s2
D) 186,000 miE) 32ft/s2
Answer: EDiff: 1
25) A car starts from rest and accelerates uniformly at 3 m/s2• A second car starts from rest 6.0s laterat the same point and accelerates uniformly at 5 m/s2. How long does it take the second car toovertake the first car?
A) 24.0 sB) 12.2 sC) 35.0 sD) 18.9 sE) 22.7 s
Answer: EOiff:2
6) A toy rocket is launched upward with a net acceleration of 10m/s2 for 3.0 s. It then slows at the rateof 10 m/s2 until it reaches its maximum altitude. How high does it go?
A) 90mB) 30mC) 15mD) 60mE) 45m
Answer: D
Diff: 1
29) In a test carried out by a car manufacturer, a test driver is asked to put on his brakes when awarning light is suddenly flashed on in the roadway ahead. When traveling 25 m/s the driver is able tostop in 98 m, and when traveling 10 m/s he is able to stop in 32.5 m. Assuming the driver's reactiontime is the same in each case, and that the rate of deceleration when the brakes are applied isindependent of speed, determine:
(a) the driver's reaction time.(b) the driver's deceleration.
Answer: (a) 2.8 s(b) 11.2 m/s2
Diff:3
23) A car starting from rest moves with constant acceleration of 2 m/s2 for 10.0 s, then travels withconstant speed for another 10.0 s, and then finally slows to a stop with constant acceleration of-2m/s2. How far does it travel?
A) 400mB) 100mC) 500m0) 300mE) 200m
Answer: Ao iff: 2
30) A car slows uniformly and comes to a stop after 10.0 s. The car's average velocity duringacceleration was 50 km/h. What was the car's acceleration while slowing down?
A) 10 km/h-sB) 5 km/h-sC) 9.8 m/s2
0) 8 km/h-sE) 4 km/h-s
Answer: AOiff:3
18) A skydiver jumps from a high-flying plane. When she reaches terminal velocity, her acceleration
A) is essentially zero.B) is approximately 9.8 m/s2 downward.C) is in the upward direction.0) is approximately 9.8 m/s2 upward.
