Suppose that an object travels from one point in space to another. Mj0 jg iu+0b:mgake a comparisg+j i0g:jbum0 on between the displacement and the distance traveled.

  When is the average velocity of an object equal-iu5g.+/.e dogp wn kq2ly:ae to the instantaneous velocity?

  A new car manufacturer advertises that their car can go "*b)4,l ,ya) 4y r*wyvql anyqrfrom zero to sixty in 8 s". This is a description ofa)b)nqy ,* *vyalwyl q,44yr r

  An object moving in the +x axis experiences an accel0ysbi7;cs. wj c7nj+ aeration of $2.0 \; m/s^2$. This means the object is

  Suppose that a car traveling to the Eas8o4wf4baomavjpk 1241 s eo:vt (+x direction) begins to slow down as it approaches a traffjom 42a1e oo4:v8 aw bs1pkf4vic light. Make a statement concerning its acceleration.

  Suppose that a car traveling to the West (-x direction) begins to slow downuo )mqj1lgz j;bzv2udza dj54r27;/ x as it approam 2;v12qb gjluz54zjj x)d7od/z; uraches a traffic light. Make a statement concerning its acceleration.

  Suppose that an object is moving with a 6ba z;u2i 7srzconstant velocity. Make a statement concerning its acceleration7bz zu;a62irs .

  If the velocity of an object is zero, does it mean thaqhr /a 5k;et+:jdcl q.t the acceleration is zero? Support your answer with an example5c :kjqtl;qe/ar dh+. .

  Can an object's velocity change direction when its acceleration is constantc:j sk8 rs jeniy39w31? Support your 3 jks3rj :1nc8is we9yanswer with an example.

  Suppose that an object is moving with constant acceleration. Make a szz- w-w8w +zmdtatement concerning its motionw8 w+-zzwd-mz with respect to time.

  Can an object have increasing speed while its accele,g.v:n s.k+g lsglfl (ration is decreasing? Support your answ,gl .nlk .l+sggv:s f(er with an example.

  Suppose a can, after an initial kick, move 9g serakqz,m(/jz ky+hgws 9i5v6e;3 s up along a smooth hill of ice. Make ay, j(sha z5e/9r 3+iv;9g6qzkws kmge statement concerning its acceleration.

  Under what condition is average velocity equal to the average of the object' ox jlk2+u5)zts in+2ukjlzoxt5 )itial and final velocity?

  Objects A and B both start at rest. They both accelerate at the same rate. q, cjz1qx4h-b However, object A accelerates for twice the time as object B. What is the1 xjzq,b-4hcq final speed of object A compared to that of object B?

  Objects A and B both start from rest. They both accelerate at wgx,qlh:s gz*j0 f ixk f*+i.8the same rate. However, object A accelerates for twice the time as object B. What is the distance traveledi+f. w0 ,k gq*zxls:jix8hf *g by object A compared to that of object B?

  When an object is released from rest and falls in the absence of frictiotmbds5p;*2 m+0x zaurn, which of the following is true conzu2x*sd;5tbr+ma m p0cerning its motion?

  When an object is released from rest and falls in the absenceg6e +sdewj40q of friction, which of the following is true conc064j eegqdw+s erning its motion?

  Suppose a ball is thrown straight up. Make a statement ax+a 3 pypu z9z zobp;:33rcsw9bout the velocity and the a 9wupa p+xzz3cp zsb3 y:9;or3cceleration when the ball reaches the highest point.

  Suppose a ball is thrown straight up. .3cl t+oy imz pafvzb2o;g6v 4 l(;:xk What is its acceleration just before it reaches its highest pk+x 4tl pcvbz.i l(oa 36:2;;fgmyovzoint?

  Suppose a ball is thrown straight up, reaches a maximum height, thenwg*b 96to3nmlbs 9/c kbj ( (g2baugt/ falls to its initial height. Make a statement about the direction of the velocity awg6m 9bubkjog/(bt 39/ g*ctl2a n(sbnd acceleration as the ball is going up.

  A ball is thrown straight up, reaches a maximum f m c/p0vioxw--5uiw0)j.ja z height, then falls to its initial height. Make a statement about the diico fjuajw -pzv.0m-i /x0)w5rection of the velocity and acceleration as the ball is coming down.

  Suppose a ball is thrown downward in * dvhdxxixaq2ex/ mb*3 pd(4/the absence of air resistance. Make a statemenqdip*/xxa3( 2m*bh d ved/ 4xxt concerning its acceleration.

  Suppose a skydiver jumps from a high-flying plan rbvzsdbd)pofc bp089w++1 n+e. What is her acceleration wheo +)cvrpd+bsn dbw0+ f18z9 pbn she she reaches terminal velocity?

  A ball is thrown vertically upward with a speed v. An identical second b+ ;6g8n0s- -rfbi6( wxfczcjt5 vq1l*oijx wkall is thrown upward with 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 sec-j-x5t zfxc 0i; oilqc*v +fsn16gk(8bjrw6wond ball go than the first ball?)

  Ball A is dropped from the to/cg 3t.-xk s)mqk 5zcmp of a building. One second later, ball B is dropped from the same building. As time pc mz3q /.ksx5)tgm-ck rogresses, the distance between them

  Ball A is dropped frk w)+yu0 tlcm22ze2q lom the top of a building. One second later, ball B is dropped from the same building. As time progresses, the differul w eqlc)tk02+ym 22zence in their speeds

  Two objects are thrown from the top of a tall building. One is thrown uprscd(z):ntx jtvqho*d8xr --*6 fuz8, and the other is thrown down, both with the same initial speed. What are their speeds when they h8n rj8t 6-hfrzo*x)*vz( s c:udt-qd xit the street?

  A brick is dropped from the top of a building. A second br.kf ;2e2(p;; hrl92whoevoinl/aiba ick is thrown straight down from the same building. They are released at the same time. Neg;2 a;na;9e lfo o(p/ei2h.hv2kribl wlect air resistance. Compare the accelerations of the two bricks.

  An object is moving with constant non-zero velocity in the +x axitli;qxb26 0s vs. The position versus time graph of tt6 ql02;bvxs ihis object is

  An object is moving with constant n .gfaoat6.i;x on-zero acceleration in the +x axis. The position versoa;.. 6ftigx aus time graph of this object is

  An object is moving with constant non-zero velocity in the +x w:3ase p zycw- qzt-2(t xt(-kaxis. The velocity versus time graph of this:wzqp2ws -(k t -- (x3tcteyza object is

  An object is moving with constant non-zero acceleration in the +x axis. akup5991 xhy47zdp-,q+zg2vwyo w xk The velocity versus time graph of this object iwux42kv ypa kqd gx,z1yo h9z+w-p957s

  The slope of a position vvhck7v2):.dkxs* e s tersus time graph gives

  The slope of a velocitgjtfz 92w89o+; mwht3q yvwkx+/ kymvj:))pzy versus time graph gives

  The area under a curve in a yer2k y-0 pxn4lx-:pvn acceleration versus time graph gives

  The area under a curve in a veloc 9khc* ru z e7fp.s73t/d5khee9koaq 7ity versus time graph gives

  If the position versus time graph of an object is a horizontal line, the objectz+n:-ddumj1yex6mrsu: j. ox;z +o+h is my1od-x+u+ jrze:+nmuz;ox.j 6: dsh

  If the position versus time graph ofdt-rh8,;:j uukc /qv q an object is a vertical line, the object isj/:udq- kr8 tv hqc,;u

  If the velocity versus timhj.xuj v c2sm*g)++ws e graph of an object is a horizontal line, the object +jvm)s*2uxc. sh jg+ wis

  If the velocity versus time graph of awyrvm+d+ o tcfuy17 q/:.nw.vn object is a straight line making an angle of 30 degrees with tm u/v vyd on+ tw1qfc+.:wy.r7he time axis, the object is

  An object moves 15.0 m north andiy4xr3z :(cq lpxmkzds.y+ ya/ 3 9n8i then 11.0 m south. Find both the distance traveled and the magni 9 zp4xnk:ys ryx3+c(q8zim3dli .a/ytude of the displacement vector.

  A boat can move at 30 km/h in still water. How long will it take 660keanwhrso0*0h eu to move 12 km upstream in a rivw 0o0eh*0kun6 se hr6aer flowing 6.0 km/h?

  55 mi/h is how many m/s? (1 mi9 u,zgi-o5eto = 1609 m)

  What must be your average speed in order to travel 350 km in 5.15 hc(9pb z24 j8z+k(b nhuab end-kvi97h?

  A runner ran the marathon (approximately 42.0 km) in 2 hours and 57 min. Whyc2/9b j 7zniiu )4pmeat is the average sp2bumpi74 cny)e j9z/ ieed of the runner in m/s?

  A car travels 90 km/h. How long does it take for it to zs /we z3bi0v, unxla6b6( x9k/ss4latravel 400 km?

  A ly (light year) is the dist)gwf mxrk5r uj86a0-c/saof;ance that light travels in one year. The speed of light ;gx u0w6ra)jo8s5k-/frm fca is $3.00 \times 10^8 \; m/s$. 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 str9mzamg k/ wwwq.vcd+e )v)3u*aight road and you look to the side for 4.0 s, how far do you tr)m 9d *u a.vwmq )wk+vegcw3/zavel during this inattentive period?

  If you run a complete loo*prp4u3 b8tx jvhbdcy09 3q/ep around an outdoor track (400 m), in 100 s, your avera b 3vjby98qr u0dx*ep/h4tc3p ge velocity is

  A polar bear starts at the North Pole. It travels 1.0 km south,4xo1rs ;f 6w74y ljpzx then 1.0 km east, then 1.0 km north, t441x xfjwl6so y rz7;phen 1.0 km west to return to its starting point. This trip takes 45 min. What was the bear's average speed?

  A polar bear starts at the North Pole. It travels 1.0 km south, then 1.0)r .qb hq3p:tzy:+nef km east, then 1.0 km north, then 1.0 km west to return to its starting point. T3z).h p:fqrq:t be+nyhis trip takes 45 min. What was the bear's average velocity?

  You are driving home on a weekend from school at 55 mi/h for 110 miles. It thre;+q2ln 9 x. j)i yu3w2mwhtzen starts to snow and you slow to 35 mi/h. You arrive home after driving 4 hours and 15 minutes. How far is your hom9xw u)tql; hr23z+ .2wieyn jmetown from school?

  A motorist travels 160 km at 80 km/h and 160x;azz3c8vy 7zxc39 vu km at 100 km/h. What is the average speed of thzcx; 9caz3v3v y78uz xe motorist for this trip?

  A motorist travels for 3.0 h at 80 km/h and 2.0 h at 100.mp b+ kx,ond. km/h. What is her average spk bn. mo.pxd+,eed for the trip?

  An airplane travels at 300 mi/h south for 2.0m x(ev*)uwlo )gztynj): g0m2) gv )xq0 h and then at 250 mi/h north for 750 miles.qm)0(eglx tv)gwjgx*) uny z)2m:v)o What is the average speed for the trip?

  In a 400-m relay race the anchorman (the person who runs x3 lye dq(04xwthe 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 ruxl 04dqyxew3(nner can have when the team A runner starts the 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 11 s.svcst3oh00 0q The car's average velocity during deceleratio03 hovst0qc0 sn was 71 km/h. What was the car's deceleration while slowing down?

  An airplane increases its speed fkfqy2rzig(8k;c yh:ef6fx jm23 :y l7rom 100 m/s to 160 m/s, at the average rate of 2kfyckifh ( 38 ye:l mf2qyjx76 :grz;$15 \; m/s^2$. How much time does it take for the complete increase in speed?

  A car traveling 60 km/lfh 2w9/;hv vp+ bvf8bh accelerates 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 acceleratehnx:y8vcit ts6gi.fd u,02d /8fcd 1h s 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 10 s. It then speeds up with a constant accelhyj bq 2z417s4 ldj.+abr9 vfzeration . ybzf+hja b2j1l 94zrds74qv of $2.0 \; m/s^2$ for 15 s. At the end of this time, what is its velocity?

  A cart with an initial velocity of 1.7 m/s experiences a co6 7cvksnhm /ri0(( pn ac6i (a*vk5 u:deus1cnnstant acceleration ofrvnknaic66ds (hc0i1( u(a* n7ves pkcu:5m/ $3.4 \; m/s^2$. What is the cart's displacement during the first 5.0 s of its motion?

  A bullet moving horizontal 3z1hptuidc3b 5*7h kcly to the right (+x direction) with a speed of 489 m/s strikes a sandbag and penetrates a distance of 88.77 bhch13c *pu kizt73d5cm. What is the average acceleration, in $m/s^2$, of the bullet?

  A jet fighter plane is launched from a cats0//4m9kyv.kw v fmb xapult on an aircraft carrier. It reaches a speed of 42 m/s at the end of thv 9mk.vy4f0/b/mxks we catapult, and this requires 2.0 s. Assuming the acceleration is constant, what is the length of the catapult?

  A car starting from rest moves with cc0g -1 u-dhzl nc5z5mtonstant 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 distance of 200 m. What is ,. ;l 7qebibaxc12dqsits average accqdbaqli s e1;c2.7,xbeleration?

  An object starts froms)qj v ap5wm ggcas+g m5v/0;kko(l1 + rest and undergoes uniform acceleration. During the first j1kmvsm5w/l+p5s k )(gqagg; ca v+o0second it travels 9.2 m. How far will it travel during the third second?

  An object is moving in a straight line witu8qunk d. :7 0tx1iteqh constant acceleration. Initially it is traveling at 16 m/s. T .in :xqudt7u01t keq8hree seconds later it is traveling at 10 m/s. How far does it move during this time?

  A car starts from rest and acc/i ,af,rjp-kt kw49 ypelerates uniformly 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 dry road can deebusz h 5;d()-) y87a-se ryyqgp vo-dcelerate 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 turu26bxg(7:vouj:9, c z a pwhfvns green, a car that has been waiting at the intaghpc9z b,x2o(v67: jv: uwufersection starts ahead with a constant acceleration 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 su(9wuf bc+p:f iw5,m cpeed of 12 m/s on the surface of planet X where the acceleration duewcc,i+u:f5fw9p b( um to gravity is $1.5 \; m/s^2$. What is the maximum height reached by the object?

  An object is thrown upward with a speed of 12 m/s on the surface of planelnf k67zhor7r60 +sojt X where the accelerationojso6nr6l7 +z 7 hk0rf due 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 speediz7hjj :y()n e of 15 m/s on the surface of planet X where the accelerationye7h: iz(j) jn 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 upwal44y6 t zz1ds-cdjuipnx+; ke vhc38*rd with a speed of 14 m/s on the surface of planet X where the acceleraisuzjz-3+y1cehp * 64td 4kn;8vld c xtion 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 frienp2gps9q,nd. zd holds a ruler between your fingers and releases it without warning, how far cqg.9 d,p2 snzpan you expect the ruler to fall before you catch it?

  A ball is thrown upward at:cg2 7nzbf38bo zqt f+c 1x7zl a velocity of 19.6 m/s. What is its velocity after 3.00oqfcfczg37bt+:n 71x lz82bz s?

  A bullet shot straight up returns/t nkkg9qaa2k p.hg;r ig(:)dt;k,n y to its starting point in 6 s. What is the initial speed of t:kk nkq r a2ha9(p)k,gyt.;t g d;/nighe bullet?

  A ball is thrown straight up with a speed of 36.0 m/s. How long does it take toqhpoq*9 p z.8 awwog5: return a 5gpow.wo q89*zhq:pto its starting point?

  A ball is thrown downward from the top of a building with an initiq0fel+5 fy 491yzeyywsg)c 1pwo)ne 6h9f6zwal speed of 22 m/s. It strikes the ground0) 1zw fh9z+ o4l6 9fpg1cye6qywy wyfsen5e) after 7.8 s. How high is the building?

  A ball is thrown straight up with a speed of 30 m/s. (only fill in numericalk k/0*ql n*nj/u-unha value in the blan /ukhj 0/nn-qal*kn*uks)
(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 znh6.s wk* ulso4(k0mthe air with a speed of 39.4 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 3 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 the velocity s ixzn 4ax;)iyc47;j qat t = 1.0 s?

  In Fig. below, what is+/n 0nxbdgt1s5 w4 h vt9+dudi the velocity at t = 2.5 s?

  In Fig. below, what is the velocity at t = 4.0 tde0*zpo x e56s?

  In Fig. below, what is the velo0/ vrsus5uc6hbf l;w ;city at t = 5.5 s?

  In Fig. below, what is the average velo1/aekioo,zj* el w) :lcity from 0 to 4.0 s?

  In Fig. below, what is the average velocit bjgzhb//f wt+) mu, al;ok4p6y from 0 to 6.0 s?

  In Fig. below, what is the acceleration at(he,l.mle 9w,phssa waa6d; - 1.0 s?

  In Fig. below, what is the acceleration czv x+pu2r(gnjykrh8rs0 +y6 934pvl,5 qrb wat 3.0 s?

  In Fig. below, what is the e3t;pyxr r, deqw.g,+average acceleration from 0 to 5.0 s?

  In Fig. below, what is the7h(.awx1j kcth3w h6(r kn cn5 average acceleration from 0 to 8.0 s?

  In Fig. below, what is the displacement from 0 to 8zj7zpb 5 f-6nekm .rq,lbj p(0.0 s?

Does a car speedometer measure speed, velocity?59mju1 20 zxmaq-)sb *amqbmx {speed|velocity}

  An object can have a varying speed nq1yvs3i5m 2pif its velocity is constant.

  The velocity of an object can be negative when its acceleration is positiv x3d4w a2( optyt*h+wwy-(0eo6dz.9 mt z udxce.

  If one object has a greater speed than a second object, the fir;wpd6 tgo(+eto :qpt 9b9en:u st must have a greater accw6o d9eg:p9qbont u t+ et:(;peleration.

  Two cars emerge side by side from a tunnel. Car A is traveling with a 6u4m h8 qeupd;v1u1g xpkg2g 44xh8 tpspeed 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 i/hpgx,3k h86/vcr cwmg. 1td kn speed as its acceleration decreases.

  A baseball player hits a foul nxcw+*8q: kxz( sh8rnball straight up into the air. It leaves the bat with a speed of8:c z8x wsn+h(n qrx*k $120 \; km/h$. 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 object speeds up, what is happen76wsrln:p k88rx1mfk ing to its acceleration, how does it change if awxkm:p n8lrs1 8k 7fr6ir friction is ignored?

  As a freely falling obje7p q+zuoyx-c4sf. w a3ct speeds up, what is happening to its acceleration, how does it change if air friction CAN NOT be ignoryfc3-zsxpoq .u 4 7w+aed?

  An object that is thrown vertmstz 89.3w wavyakoo(0a jn- 5o xq9*yically upward will return to its original position with the same speed as it had initially if air resist-ya(on8o9jv ka50t 3sao qww*mxy.z9 ance is negligible. If air resistance is appreciable, how will this result be altered?

  An object can have zero velocity and nonzero acceleration at the samex z pur6p5e4/h time.

  An object can have nonzero velocity and zero a34p hzthfl :f2cceleration at the same time.

  An elevator moving from the second floor 7/qzi ,w fqrnf0mj :*bto the fifth floor making no stops along the/zj7fw0*q: m, f qnrbi way has zero acceleration all the time.

  A rolling ball moves :c(hjd/n qm-. 4tkmf nfrom $x_1=2.5 \mathrm{~cm}$ to $x_2=-5.1 \mathrm{~cm}$ during the time from $t_1=2.4 \mathrm{~s}$ to $t_2=5.9 \mathrm{~s}$. What is its average velocity?  (数值)  $cm/s$ (only fill in numerical value please)

  A particle at $t_1=-2.8 \mathrm{~s}$ is at $x_1=2.4 \mathrm{~cm}$ and at $t_2=3.2 \mathrm{~s}$ is at $x_2=8.2 \mathrm{~cm}$. What is its average velocity?  (数值)  $cm/s$

  A person jogs eight complete laps around a qujmen*:wbes h 5,k :f0iarter-mile ($1 \; mile = 1609 \; m$) track in a total time of 11.5 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 straig3,c7m*ysodq fht line, moving 89 m away in 13.7 s. It then turns abruptly and gallops halfway back in 4.5 sy3 d 7s,oqfcm*. Calculate (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 from6po-udx+5b r x 1zmo7m $11 \; m/s$ to $22 \; m/s$ in 5.5 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 fro+ 3:tj1vc . mch.ywazam $20 \; m/s$ to rest in a distance of 78 m. What was its acceleration, assumed constant?  (数值)  $m/s^2$

  A light plane must reac6zdg) oag3p1oh a speed of $32 \; m/s$ for takeoff. How long a runway is needed if the (constant) acceleration is $2.4 \; m/s^2$ ?  (数值)  $m$

  A world-class sprinter can burst tvg3e1dea1 d6/:tpia)2i x 5 nv)xfsgout of the blocks to essentially top speed about)ede i) x1p/ d xvaisgta3nf21vg:5t 6 $10.1 \; m/s$ in the first 12.6 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 unifov -q 9su4cw;aurmly from a speed of $20 \; m/s$ to rest in 5.39 s. How far did it travel in that time?  (数值)  $m$

  In coming to a stop, a car leaves skid marks 92 m long on the yxgw ,ej- 1 1xx0hpk:nhighway. Assuming a deceleration x10kj1egp : xwhn,y-xof $7.00 \; m/s^2$, estimate the speed of the car just before braking.    $m/s$

  A car is behind a truck w5zz henmavtf89,4a: k n94(dl) fostgoing $25 \; m/s$ 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).    $m$