Suppose that an object travels from one point in space to another. Makg.m*/ k8psdr p w07svoe a comparison betweenm s8vwgors.*k70/dpp the displacement and the distance traveled.

  When is the average velocity of an objkz 4lj4 .w lt9jx pnyv kzpi.38k;;,)n,o eehhect equal to the instantaneous velocity?

  A new car manufacturer advertises th- jhkk- h;ga/v/wit* oat their car can go "from zero to sixty in 8 s". This is a description o/ ahj-/ti-wvkhko *;gf

  An object moving in the +x axis experiences an acjyaly-6 :/rff /9ctt e pm*y/nceleration of $2.0 \; m/s^2$. This means the object is

  Suppose that a car traveling to the East (+x direction) begins to sydcrt/ t47jy kmpiyk.- i,x *kw7/w4s low down as it approaches a traffic light. Make a statement concerning its acceleratiks .cki yptyx-wkr7,7it4y/d*/mj4 w on.

  Suppose that a car traveling to the Wes v)pwg+6ws4e qt (-x direction) begins to slow down as it approaches6 gvsqww4pe)+ a traffic light. Make a statement concerning its acceleration.

  Suppose that an object is moving with a constant velocity* 9s2 iv bdxr-hf0tc-f. Make a statement concerning itshftd *r9 v-ifbs2-0cx acceleration.

  If the velocity of an bll)3cy;)iv1-a qa ag-vj2d+e6gvnb object is zero, does it mean that the acceleration is zero? Support your answer naq+bagvabd 1l6vc l g3eyvji 2; ))--with an example.

  Can an object's velocity change direction when its acceleration is(e*rdq n92- vfkfhze: constant? Support your answer w v2(-9zne*qf:r dkf ehith an example.

  Suppose that an object is moving with cons,av,o )zv3 zjitant acceleration. Make a statement concerning its mij,)oz3,avv zotion with respect to time.

  Can an object have increa/j+o5q*jq8c jz 0 x(.dc;evxhhxd j8asing speed while its acceleration is decreasing? Support jecqzxo 8jhqcxv8d (5*; j0jx+. d/hayour answer with an example.

  Suppose a can, after an initial nj t 8zw.8ujxx2fcoyh; +lq31 kick, moves up along a smooth hill of ice. Make a statement concerningwzf+ht2 ux38j n;c yx8j.qol1 its acceleration.

  Under what condition is average velocity equal toxne 133ptdau:i :/k de the average of the object's initial ant3ipdkene13:a/u:d x d final velocity?

  Objects A and B both start at rest. They both acc.16p8 t ,sheedq fak)delerate at the same rate. However, obp, dsd)ka6e te.q h8f1ject A accelerates for twice the time as object B. What is the final speed of object A compared to that of object B?

  Objects A and B both start from rest. They both accelerate at the sllo,7nc (vvp.e;a splxl*4r)ame rate. However, object A accelerates for twice the time as object B. What is the distance traveled by object A compared to;7lr .)o p,4(llxcna ls*vvpe that of object B?

  When an object is released from rest and falls +hbbei;r *aeygfs *0,owi(tbe ,9a d+ in the absence of friction, which of the folleafbr+9 ,(t,a sd;*og+* bhyei ibwe0owing is true concerning its motion?

  When an object is rele l8n l4lijw5 r49pf,jhased from rest and falls in the absence of friction, which of the 45jjlw98lhi4lrf p,nfollowing is true concerning its motion?

  Suppose a ball is thrown strai c4,af- huj.e co6,mb 3wxo*bkght up. Make a statement about the velocity and the acceleration when the ball reaches the highest point.6o focakmehbbu *-,x,3 4.jcw

  Suppose a ball is thrown straight up. What is k0uq:j;c-xohy kt 1 p/its acceleration just before it reaches its hipyo;uj-/ 0h tk:cx1kq ghest point?

  Suppose a ball is thrown straight up, reachtqt5/0h5 fy alse(f7c es a maximum height, then falls to its initial height. Make a statement about the direction of the velocity and acceleration as the ball is going (f7y tca l5qht/fe50sup.

  A ball is thrown straightv /2rp3ltozg 0 up, reaches a maximum height, then falls to its initial height. Make a statement about the direction of the velocity and acceleration as the ball is coming dotp r0v go/2l3zwn.

  Suppose a ball is thrown downward inj,:vyy;l bsp2 the absence of air resistance. Make a statement concerning its acceleration.y2l :pj v;s,yb

  Suppose a skydiver jumps7o* hb6wv ui4nny ;,dy from a high-flying plane. What is her acceleration when she she reaches terminal ve ,6;hoyduwn*4nb 7v yilocity?

  A ball is thrown vertically upward with a speed v. An identical sp7d8ja 5my9+uof*tu zkrwg, .econd ball is thrown upward with o.8fgd5wr mkza7 9+u *tupjy,a speed 2v (twice as fast). What is the ratio of the maximum height of the second ball to that of the first ball? (How many times higher does the second ball go than the first ball?)

  Ball A is dropped from thzc1s ) ,wi0sa.v:kbq4gj jwb3 ym;pd7 e top of a building. One second later, ball B is dropped from the same building. As tiwzijygd.p ab 03 sjkqb1vw,c:m7 s;4)me progresses, the distance between them

  Ball A is dropped frommcj7a dliu2mb q/;u30 the top of a building. One second later, ball B is dropped from the same building. Asm;ad2b ju0/ l 37uiqmc time progresses, the difference in their speeds

  Two objects are thrown from the top of a 9r;(hf cr ioxhb1 *i;ptall building. One is thrown up, and the other is thrown down, both with the same initial speed. What are their speeds when the ;hcirbhp(xf *ir9o;1 y hit the street?

  A brick is dropped from the top of a building. A second b,u/b3p:kr xju)fth:s rick is thrown straight down from the same building. They are rt :3hsrfb:)ujp ku,x/eleased at the same time. Neglect air resistance. Compare the accelerations of the two bricks.

  An object is moving with constant non-zero velocity in the +x ax fm1rt d fzg0247o6upuis. The position versus time graph of this 2 4t6oz f d0rufpmg1u7object is

  An object is moving with constant non-zero accelf 9 /*/obr9qs1mmj+:bq2a jb tybdz7seration in the +x axis. The position versus time graph of thia+9b2b j bjq /rosmzs/tq1f9*:m7 byd s object is

  An object is moving withlvr (ka5/uq h:s,w2l4io:zhq constant non-zero velocity in the +x axis. The velocityv :4zorsl 2wq/hl q(:5uha k,i versus time graph of this object is

  An object is moving with couo+d m vx7 m39zhkuh+k:.,*epa8d c bonstant non-zero acceleration in the +x axis. The velocity versus time graph of this ob3m d emu+,c k789h:kaz+.*ohpudobvxject is

  The slope of a positiqfg zmc) uc:0x(wt1xq1dp3h 1on versus time graph gives

  The slope of a velocity versus time graph ga 6 ,m(ip1osauives

  The area under a curve in an acceleration qwe,6q dhxlop94;7; iyy8awp versus time graph gives

  The area under a curve in a velocity versus time graph gi hz8ljh: 6l1gxjg q(m6ves

  If the position versus time graph of an object is a horizontal lf5vw )hsnw :l0ine, the object i:0nhww 5)v lfss

  If the position versus time graph of an ok6 4g4i)(- zgoh crxqnd *ing*bject is a vertical line, the object isc dnkzi6*nhxiqg4 g r4-(o*g)

  If the velocity versus time g.gimf*q b2ii u-ih.:ge g4 a.avutb: -raph of an object is a horizontal line, the object qa:. egif .g-gubtihiim.:v au4-*b2is

  If the velocity versus time graph of an object is a s1y1y;1 ymi(v40: umbltb iwbttraight line making an angle of 30 degrees with the time 0tytm(y uilw;b b:41b m11yivaxis, the object is

  An object moves 15.0 m north and then 11.0 m south. Find botkoc1. ua z1jn9,f-nyeh the distance traveled and the magnitude of the displacementkyouj1n e za9-nc,.f1 vector.

  A boat can move at 30 km/h in still water. How8j .q1 jfojv.4yej,ap long will it take to move 12 km upstre.ef.8ja4 o ,1yvpjq jjam in a river flowing 6.0 km/h?

  55 mi/h is how many m/s? (1 hoo9tr7j: ex;sz:,yp/i ts h 6mi = 1609 m)

  What must be your avr76fnljrw: 60v+ 2ws0y7ny ru:rw i eaerage speed in order to travel 350 km in 5.15 h?

  A runner ran the marathon (approximately 42.khel3ud8b5 x20 km) in 2 hours and 57 min. What is the average speed of the runner in m/s?ek5uxd lh2b3 8

  A car travels 90 km/h. How long does it take for it to travel(w3z:-hb3xt, k vv7xml5dl5r cbn:iw 400 km?

  A ly (light year) is the distance that light travels in one year cxhd:i m2bwm*kt8, zpfch;ta.m,2 io4i a7 4e. The speed of light i,aie itx w.4m;hzo2p74fc2m*:k8a hmcb,t dis $3.00 \times 10^8 \; m/s$. How many miles are there in a light year? (1 mi = 1609 m, 1 yr = 365 d.)

  If you are driving 72 km/h along a straight road and you lookn1kg 9:q3b wd 9a*c:nf-nq xwf to the side for 4.0 *1w dabcx 9g nfnq9kq nf-3::ws, how far do you travel during this inattentive period?

  If you run a complete loop around alv 00aou l;re8qrnbv; .zqo)0c pp:4yn outdoor track (400 m), in 100 s, your average velociq4 b0:rz;vp;r. lepoon0)v y0al uq8 cty is

  A polar bear starts at the North Pole. tyt/vv 7i 0xb uv2l62dIt travels 1.0 km south, then 1.0 km east, then 1.0 km north, then 1.0 km west to return to its starting point. This trip takes 45 min. What was the bear's average speedviv6t l2tydb7 0u xv/2?

  A polar bear starts at the North Pole. It travels 1.0 km south, then 1.0 k2/( cmppegyil t .4v:b28aai4zssqt)m east, then 1.0 km north, then 1.0 km west to return to its starting point. This trip takes 45 min4 )yi2t8( 2 bppzcm/v a.gi 4qstelsa:. What was the bear's average velocity?

  You are driving home on a wekjhk3ei . b1ds::eqb;-xq ca8ekend from school at 55 mi/h for 110 miles. It then starts to snow and you slow to 35 mi/h. You arrive home after driving 4 hours and 15 minutes. How far is your hometown from sch b.k1 ki;ja8bh 3cx:eq: eqsd-ool?

  A motorist travels 160 km at 80 km/h and 16( bfuqj w9n()w0 km at 100 km/h. What is the average speed of the motorist for this trip? )ju ((wwnfbq9

  A motorist travels for 3.0 h at 80 km/h and 2.0 h at 100 km/h. Wh2 b6os+vhc g4am1 bovc osm98*at is her average speed for the trip2 s1gs+ 8oabmbv *vo46m9chco?

  An airplane travels at 300 mi/h south for 2.00 h and1v6 m9r8mcdjjwq;(wk then at 250 mi/h north for 75 j;wmkjm6r9d1c(v q8w0 miles. What is the average speed for the trip?

  In a 400-m relay race the anchormanlnvqd0wi:n +0+ 8l.dsv z nv.bhx60 bb (the person who runs the last 100 m) for team A can run 100 m in 9.8 s. His rival, the anchorman for team B, can cover 100 m in 10.1 s. What is the largest lead the team B runner can have when the team A runner starts the6:+0ds nvibnn0.lblv qvb.whd8xz +0 final leg of the race, in order that the team A runner not lose the race?

  A car decelerates uniformly and comes to a stop after 8 s. The caq kybx2ky qf-oz6+l(0d ve6(yr's average velocity during deceleration was 41 kq6b-y (x2z0yk e y( okqldv+f6m/h. What was the car's deceleration while slowing down?

  An airplane increases its speed from 100 m/s to 160 m/s, at the average rate g ee8i8g/uw.wpj)zd0of ./gzjd gepe)w8 08iu w$15 \; m/s^2$. How much time does it take for the complete increase in speed?

  A car traveling 60 km/h acc .vql1vsdwe 0po nr6)-elerates at the rate of $2.0 \; m/s^2$. How much time is required for the car to reach a speed of 90 km/h?

  A cart starts from rest and accelerawm;g0)mc f(wates at $4.0 \; m/s^2$ for 5.0 s, then maintain that velocity for 10 s, and then decelerates at the rate of $2.0 \; m/s^2$ for 4.0 s. What is the final speed of the car?

  A car travels at 15 m/s for yvhukq9pjl +. dma.0* 10 s. It then speeds up with a constant acceleration oap k.*h9+0. ydluqv mjf $2.0 \; m/s^2$ for 15 s. At the end of this time, what is its velocity?

  A cart with an initial velocity of 5.0 m/s experiences a constant acceleration8n dj4c;0- 2suahp eas of cssh28 pu jan d4;-0ae$4.0 \; m/s^2$. What is the cart's displacement during the first 9.9 s of its motion?

  A bullet moving horizontally to the right (+x direr rlklj 00;nb1ction) with a speed of 394 m/s strikes a sandbag and penetrates a distance of 71.37 cm. What is the averl 0k;1nl0brrjage acceleration, in $m/s^2$, of the bullet?

  A jet fighter plane is launched from a+a zz e6mvc2 pyk7*6.xuz ex6j catapult on an aircraft carrier. It reaches a speed of 42 m/s at the end of the catapult, and this requ6.2yejpk z6auz c ex*zx76+ mvires 2.0 s. Assuming the acceleration is constant, what is the length of the catapult?

  A car starting from rq/+6gz:n kwtsest moves with constant acceleration of $2.0 \; m/s^2$ for 10 s, then travels with constant speed for another 10 s, and then finally slows to a stop with constant acceleration of
-$2.0 \; m/s^2$. How far does it travel?

  A car goes from 40 m/s to 80 m/s in a dist(o3xth- w hxy-ance of 200 m. What is its average acceleration?xow- 3xy(- hht

  An object starts from rest and undergoes uniform acceleration. During hl)j qg)o0e.athe first second it travels 1.9 m. How far will it travel during the third seco) h0.oaqelg) jnd?

  An object is moving i d qpqwnb-)oz83as2w0n a straight line with constant acceleration. Initially it is travelinnd p -)wb2wzso8q0 qa3g at 16 m/s. Three seconds later it is traveling at 10 m/s. How far does it move during this time?

  A car starts from rest and accelerates uniforkz b gu*jm-q;9k +lao1i*liz;mly at $3.0 \; m/s^2$. A second car starts from rest 6.0 s later at the same point and accelerates uniformly at $5.0 \; m/s^2$. How long does it take the second car to overtake the first car?

  A car with good tires on a dd8nur0tzv r*5f ks f* m,ecuw-3i/ ol(ry road can decelerate at about $5.0 \; m/s^2$ when braking. Suppose a car is initially traveling at 55 mi/h.
(a.) How much time does it take the car to stop?    $s$ (only input numerical values)
(b.) What is the stopping distance?    $m$ ((only input numerical values)

  At the instant a traffic light turns green, a car that has beenxm guexe(:7uq--s 4 mw waiting at the intersection starts ahead with a constant acceleratigexu(-wu q-e4xm: 7 smon of $2.00 \; m/s^2$. At that moment a truck traveling with a constant velocity of 15.0 m/s overtakes and passes the car.
(a.) Calculate the time necessary for the car to reach the truck.    $s$ (only fill in numerical values)
(b.) Calculate the distance beyond the traffic light that the car will pass the truck.    $m$ (only fill in numerical values)
(c.) Determine the speed of the car when it passes the truck.    $m/s$ (only fill in numerical values)

  An object is thrown upward with a speed of 12 m/s on the surface of planet X wheilr 3 (mppgy-rxp 2lbq-rq 310re the acceleratrq(pb13 - y 3r0-lgqp i2mpxrlion due to gravity is $1.5 \; m/s^2$. What is the maximum height reached by the object?

  An object is thrown upward with asmr1 yrnr*zy)v k*db32 cfg,yx :(t e- speed of 12 m/s on the surface of planet X where the acceleration due bd3yfk( *ycn * yev,t2s1rrg-rzx m): to gravity is $1.5 \; m/s^2$. How long does it take for the object to reach the maximum height?

  An object is thrown upward with a speed of 15 m/s on befx ;+ hn ;fs:f7-pwrthe surface of planet X where the acceleratioh:;- n; +pxb7fewrfs fn due to gravity is $2.5 \; m/s^2$. How long does it take for the object to return to where it is thrown?

  An object is thrown upward with a speed of 14 m/s on the surface of planet X wfwvt6z ; n+9e)blws; dhere the ac 9+le6zfv;)s bwtw n;dceleration due to gravity is $3.5 \; m/s^2$. What is the speed of the object after 8.0 s?

  Human reaction time is usually greater than 0.10 s. If your frk3ug(19m59vyb,0ds-/b kvqhzy:jm b em6g us iend holds a ruler between your fingers and relea -,mbz3gs9ks1 / m9jek dg:6bv (v m5qhby0yuuses it without warning, how far can you expect the ruler to fall before you catch it?

  A ball is thrown upward at a velocity of 19.6 m/s. What is its velol)xdpeed 3kcp79c j5vq+/0nrj-ij dz-a ( ,l scity after 3.00 05s)x-e(djp7l 3da j9qk,ipd nr cjlez-+ vc/s?

  A bullet shot straight up ft3b0v j; )j)hnjrzkze8c lvq)de)fhnc0+/; returns to its starting point in 13 s. What is the initial speed of the bul 0z0e;vqh)e8));r djjf3c/ cnl+vzb h tkfn)jlet?

  A ball is thrown straight up with a speed of 9r;)5 uynmb f,) ll 1bkwdhws.36.0 m/s. How long does it take to return s5kwylb;w m9,h. rd1 bnu) lf)to its starting point?

  A ball is thrown downward from e hatw6f8ixx )p: f ;0.gx )vtlt-.pwxthe top of a building with an initial speed of 29 m/s. It strikes the grx-pfh8v.etf 6;pltxwai 0 . xwgt x)):ound after 7.9 s. How high is the building?

  A ball is thrown straighpuft3lruvi;ru4o 3r. f s)r06t up with a speed of 30 m/s. (only fill in numerical value i vr ui4 u;.flrt3f3uro6)r0psn the blanks)
(a.) How long does it take the ball to reach the maximum height?    $s$
(b.) What is the maximum height reached by the ball?    $m$
(c.) What is its speed after 4.2 s?    $m/s$

  A foul ball is hit straight up into the air with a s :b7pwc 5cg8n:43zy1j rdhz jvh.ny, epeed of 44.7 m/s. (use $g=10 \; m/s^2$, only fill in numerical value in the blank)
(a.) Calculate the time required for the ball to rise to its maximum height.  (数值)  $s$
(b.) Calculate the time for the ball to fall back to the height at which it was hit.  (数值)  $s$
(c.) Calculate the maximum height reached by the ball.  (数值)  $m$
(d.) Calculate the ball's speed 2 seconds later.  (数值)  $m/s$
(e.) Determine the time at which the ball pass a point 6 m above the point of contact between the bat and ball for the first time.  (数值)  $s$
(f.) Determine the time at which the ball pass a point 6.0 m above the point of contact a second time.  (数值)  $s$

  In Fig. below, what is t1 cf j)vqf /i/jeqi7e.he velocity at t = 1.0 s?

  In Fig. below, what is the velocity at t = 2.5dn *2w k/gfle, d,4qmm s?

  In Fig. below, what is the veloci-p9r9a (gxgvyty at t = 4.0 s?

  In Fig. below, what is the v*:zpupz8m ul2elocity at t = 5.5 s?

  In Fig. below, what is the average velocity from 0 to 4.0 s?(py4jd*oelc l,us*: mp qm-7t

  In Fig. below, what is the average v;dwhvwk:eiy o-)0z 2 7k ttqb)elocity from 0 to 6.0 s?

  In Fig. below, what is the acceleration at 1.0 s?oln9: 6 cfu6zc

  In Fig. below, what is the accemm+w dzcscpe0 yk)v6x-zzq( w26 ,k; jleration at 3.0 s?

  In Fig. below, what is the average acceleration from 0 to p yx9 .ge)ht7h n60ngt5.0 s?

  In Fig. below, what is the avekk w qlm,rk vm d/8:*e+po5va6rage acceleration from 0 to 8.0 s?

  In Fig. below, what is the displacem(zmg*am x+j07c4 kryient from 0 to 8.0 s?

Does a car speedomet exz(q7v9v:ywbf(avl)w :6 d c ft2q6jer measure speed, velocity? {speed|velocity}

  An object can have a vary7(uof6 x*p pkging speed if its velocity is constant.

  The velocity of an object can be negative when its accel: ast o3.*(qefgjz pi7eration is positive.

  If one object has a greater speed than a second object, the first must hb0e*ey20 tzjt ave a greatbe2ze tjy00*ter acceleration.

  Two cars emerge side by side from 39nsajnm18m gs1 ow k0a tunnel. Car A is traveling with a speed of $60 \; km/h$ and has an acceleration of $40 \; km/h/min$ Car B has a speed of $40 \; km/h$ and has an acceleration of $60 \; km/h/min$ . Can A will pass car B at the instant they come out of the tunnel.

  An object can be increasing in speed as its acceleration d5opwia*m5b+b0 z6a cyecreases.

  A baseball player hits a h)k+zd 941jtz(gulj wfoul ball straight up into the air. It leaves the bat wkdh4wz(19u )t+j zjgl ith a speed of $120 \; km/h$. In the absence of air resistance, how fast will the ball be traveling when the catcher catches it?    $km/h$ (please only fill in numerical value in the blank)

  As a freely falling obp7a r,v97 ,v(lncpox :f rkzt8ject speeds up, what is happening to its acceleration, how does it chr7 pl, 9vkrtpoa(v7f z:nx 8c,ange if air friction is ignored?

  As a freely falling object speeds up, wxj 5f .9h1os ugttw*+:gk(8r lns5ddehat is happening to its acceleration, how does it change if air friction C:w51.gs+g( t j*trd5n8o skl9e u xhdfAN NOT be ignored?

  An object that is thrown verti7y( ba45ril i48qqtgctw+, ajcally upward will return to its original position with the same speed as it had initially if air resistance is negligible. Itwiqq agr 4 5,8+jcai74byl(tf air resistance is appreciable, how will this result be altered?

  An object can have zero velocity and nonzero acceleration at thew* 1/z umonwt1 same time.

  An object can have nonzero velocity and zero acceleratioc 5+w le.pxex0n at the same time.

  An elevator moving from the second floor to the fa bixs; r,gkxf5 ro./-ifth floor making no stops along the o;rxb/aiks- .5r xfg, way has zero acceleration all the time.

  A rolling ball moves vp45hj49x p 3uys4 rfmfrom $x_1=2.6 \mathrm{~cm}$ to $x_2=-7.5 \mathrm{~cm}$ during the time from $t_1=1.6 \mathrm{~s}$ to $t_2=5.6 \mathrm{~s}$. What is its average velocity?  (数值)  $cm/s$ (only fill in numerical value please)

  A particle at $t_1=-2.4 \mathrm{~s}$ is at $x_1=3.4 \mathrm{~cm}$ and at $t_2=3.2 \mathrm{~s}$ is at $x_2=7.3 \mathrm{~cm}$. What is its average velocity?  (数值)  $cm/s$

  A person jogs eight complete laps arounp. 6t.i ( mbfxay:hdg9d a quarter-mile ($1 \; mile = 1609 \; m$) track in a total time of 9.4 min. Calculate (a) the average speed  (数值)  $m/s$ and (b) the average velocity    $m/s$

  A horse canters away from its trainer in a straight line, moving 90 m awb ;d h2f/gsc2tay in 12.0 s. It then turns abruptly and gallops halfway back in 4.7 s. ;c2gft /db2 hsCalculate (a) its average speed  (数值)  $m/s$ and (b) its average velocity  (数值)  $m/s$ for the entire trip, using “away from the trainer” as the positive direction.

  A car accelerates from 8gr6(exswtcmd* p:.j$12 \; m/s$ to $23 \; m/s$ in 4.3 s. What was its acceleration?  (数值)  $m/s^2$ How far did it travel in this time?  (数值)  $m$ Assume constant acceleration.

  A car slows down frome/ap,j;9 ied e7ovw9 s $16 \; m/s$ to rest in a distance of 64 m. What was its acceleration, assumed constant?  (数值)  $m/s^2$

  A light plane must reach i9ka ,gr3vi*ciy* rf-.4ao byeax x(,a speed of $29 \; m/s$ for takeoff. How long a runway is needed if the (constant) acceleration is $2.5 \; m/s^2$ ?  (数值)  $m$

  A world-class sprinter can burst out of the blocks to essentially at ekyzqoy3: 00k/6 xitop speed abou0k0kxy :zeqy6a3to i/t $10.3 \; m/s$ in the first 12.2 m of the race. What is the average acceleration of this sprinter?  (数值)  $m/s^2$ and how long does it take her to reach that speed?  (数值)  $s$

  A car slows down unifollh mj o8skr -c;c:*l:rmly from a speed of $15 \; m/s$ to rest in 4.47 s. How far did it travel in that time?  (数值)  $m$

  In coming to a stop, av6cqh gnlt )vy- u)w:2n: 9hz (3mqcnc car leaves skid marks 92 m long on the highway. Assuming a decel:gm3h)th vuql6 nnc w:q(-v2z9n y)cc eration of $7.00 \; m/s^2$, estimate the speed of the car just before braking.    $m/s$

  A car is behind a trq o.aw, (t8sej3ej2ci6h r1qf uck going $25 \; m/s$ on the highway. The car’s driver looks for an opportunity to pass, guessing that his car can accelerate at $1.0 \; m/s^2$. He gauges that he has to cover the 20-m length of the truck, plus 10 m clear room at the rear of the truck and 10 m more at the front of it. In the oncoming lane, he sees a car approaching, probably also traveling at $25 \; m/s$. What is the closest distance of the approaching car that he can still sately make the attempt to pass the truck? (without hitting the approaching car).    $m$

  A runner hopes to complete the 10,000-m run in less than 30.0 min. Aftervc7jwf.oq5 gtr s qd158,xh:m exactly 27.0 min, there are still 1100 m to go. The runner must then acceler8rtf 5.q:dw71c5goj hx,vsm qate at $0.20 \; m/s^2$ for how many seconds in order to achieve the desired time?    $s$