Suppose that an object travels from one point in space to another. 2n -x13kzm fv,8sa1dkzo:zrxMake a comparison be a8f-mo3rnz:zxv1d,zskx1k2 tween the displacement and the distance traveled.

  When is the average velocity of an object equal to the 7dpgjimgv2 le-i 60/m instantaneous velocity?

  A new car manufacturer advertises that their car canv wnmobzrq4.(ps 5 2)v go "from zero to sixty in 8 s". This is a des(v5.p4b z 2moqwnrv) scription of

  An object moving in the +x axis experiences an l4fjk08 +btim acceleration of $2.0 \; m/s^2$. This means the object is

  Suppose that a car traveling to t pni tp59b5+ ps-qjkdal66,mbhe East (+x direction) begins to slow down as it approaches a traffiilj6 9ba+kb,p6 - tqsdp5m5p nc light. Make a statement concerning its acceleration.

  Suppose that a car traveling to the West (-x direction) begi9 6z rstfwl.9zns to slow down as itfsl69 9zrz.wt approaches a traffic light. Make a statement concerning its acceleration.

  Suppose that an object is moving with a constant velocity. Make k -tk:hf0d2eo;zj *et 1y)d kda statement concerning its ac d- e*0hj;tzkt:e2ykdf dok1) celeration.

  If the velocity of an objmvi*k1m5qlih, 0lr8 aect is zero, does it mean that the acceleration is zero? Support your answer wita8 1ilmqim r0*hv,lk5h an example.

  Can an object's velocity change direction whe+f r/ 4rieps(;ppn. 07rfo dunn its acceleration is constant? Support youpo/ir0ndf pfr ;(e7 .ru4p n+sr answer with an example.

  Suppose that an object is moving with constant acceleration. Make a stx kq o zz:pvls;,x*o03z:wn/uvpr4f0atement concerning its motioo x03prlpvz xkzz,;: :s/q*4ow 0unv fn with respect to time.

  Can an object have increasing speed nf(-z,ke x.jrk og8 m1while its acceleration is decreasing? Support your answer with an examplm o1eg8krkx z,.j-(fne.

  Suppose a can, after an initial kicm e;.c.1 eudxcqi5; 6z iard9yk, moves up along a smooth hill of ice. Make a statement iz.ux;mi.1a qed;dcerc5 9y6 concerning its acceleration.

  Under what condition is average velocity equal to the ab.yp3owv::hi(7 tb o pverage of the object's ini: vw( oypi:.b 37ohtpbtial and final velocity?

  Objects A and B both start at rest. They both accelerate at the same rate. u*+6sew9lxmsz v ( *yvHowever, object A accelerates for twice the time as object B. What is the final speed+*v*usx(s6z9ly w mve of object A compared to that of object B?

  Objects A and B both start from rest. They both accelerate at the same rawqzc(kf 4sj5,te. However, object A accelerates for twice the time as object B. What is the distance traveled by object A compared to thzk ,(cfw5j4sqat of object B?

  When an object is releasd1 l xs9 a:a+0takl8ueed from rest and falls in the absence of friction, which of the following e sakd+18lla9u0:ta xis true concerning its motion?

  When an object is rel4c ziv+r /r3 yrguz ,z/nno.7ieased from rest and falls in the absence of friction, which of the follownrizr7 3,on /viuzg /ry+.4z cing is true concerning its motion?

  Suppose a ball is thrown straight up. Make a statement about the vev6e *sj )lcg so5:qdx/locity and the acceleration when the ball reaches the:*dcsxvg q /s65) ejol highest point.

  Suppose a ball is thrown straight n8g,t7-ellygi 8j ; g5j7pfegup. What is its acceleration just before it reaches its highest pl 8nig egyp,-f 5j;t7g8gle7joint?

  Suppose a ball is thrownr*dj)oicp -;lh 8;hm33ph pvv straight up, reaches a maximum height, then falls to its initial height. Make a statement about the directihpv8dp-ph; * i c o3lj)3hr;vmon of the velocity and acceleration as the ball is going up.

  A ball is thrown straight up, reaches a maximum height n.fwzh9n *tfr;. j+zz, then falls to its initial height. Make a statemen .* tf nw.njfhzrz9+z;t about the direction of the velocity and acceleration as the ball is coming down.

  Suppose a ball is thrown downward in the absence of air rzlb0n63 z na3wesistance. Make a statement concerning its acceleratiow 63zan0zbln3 n.

  Suppose a skydiver jumps from as2,p n:e ) a0xdi,a; kgbryu2l high-flying plane. What is her acceleration when sr,0alxb u2s; yna e:p2),kdgi he she reaches terminal velocity?

  A ball is thrown vertically upward with a speed v. An identical second ball i8lkmp6b3 jh8sy/rc) 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 second ball go3kr8l)/bcj h6imsyp 8 than the first ball?)

  Ball A is dropped from the top s voht/ +a9w6 e7nykx;yq3a4qof a building. One second later, ball B is dropped from the same buildin qo3hy6 s/ ktvey;94 +qaa7xwng. As time progresses, the distance between them

  Ball A is dropped from the top of a building. One second later, ball B isq3sevh;6ta 3 y dropped from the same building. As time progresses, the difference in their hqs;e633a yvtspeeds

  Two objects are thrown from the top of a tall building. One is thrt6/xxl308 :wkbrr +cmwk,hu qown up, and the other is thrown down, both with the same initial speed. What arem3xtbwc,l08x rh:6qwr +uk/ k their speeds when they hit the street?

  A brick is dropped from the top of b*cr:(.zu -zl, idmfq a building. A second brick is thrown straight down fro z,r*-d(fmq :ilzc.bum the same building. They are released at the same time. Neglect air resistance. Compare the accelerations of the two bricks.

  An object is moving with constant non-zero vi rh2owo:tq*/elocity in the +x axis. The position versus time graph of this objohrti2q/: o *wect is

  An object is moving with constant non-zero 7tk),t; rp k0o6zwl gnacceleration in the +x axis. The position velzgt; pr wk6, t7)0onkrsus time graph of this object is

  An object is moving with constant non-zero velocity in the +x axis. The velocitfph7 uc);b7 -ch+uf8nx 6bgmo y versus time graph of this b-u6bcf n7o u+c7x)h8hm p;fg object is

  An object is moving with constant non-zero acceleration in the 75y:psfx9oh vw e7rr rm+r7t: +x axis. The velocity versus timrrs77:mx+e9or5 rt:pyfv h7 we graph of this object is

  The slope of a position versus tipq-;qowmcpq 3lljo3 1m31q ,ume graph gives

  The slope of a velocity versus time graph gssr.ki+x*a 7bc aadr- u; g;x7 r-;dgsives

  The area under a curve in an acceleration versus time graph givesw2a7oigade +vg mf3kwa6(0 . o

  The area under a curve iz xyuqk(ooxr o;5:t-: n a velocity versus time graph gives

  If the position versus time graph of an object is a horizontalatm-6 4i c.dwz line, the object i z4cd6awt .m-is

  If the position versus time graph of an object is aaben w7en + v(/rgozv2-g:mn9 vertical line, the object isn:n2bo e-zvn+ ga (r g79vwem/

  If the velocity versus time graph of an object is a horizontale rbg20oqk9 h5 4spch6oui u3; line, the object isro2i4gec 0uh6qk9 sb5h;3pu o

  If the velocity versus time graph of an object is a straight line making an angz3b1 l n5gqwfz *ba9g52*udhzle o zf2l51h zwg*du9qb 3ab5gzn *f 30 degrees with the time axis, the object is

  An object moves 15.0 m north and then 11(na6vsc/t (hd.0 m south. Find both the distance traveled and the magnitudev ((t/6nhcdsa of the displacement vector.

  A boat can move at 30 km/h in still water. How long will it take to movekmg61kt (cw;o 12 km upstream in a river flowingok 6gkct1;(mw 6.0 km/h?

  55 mi/h is how many u q1r*q 7raqk:bxnzor,+1h,7apoo ,bm/s? (1 mi = 1609 m)

  What must be your average sp 1hth*0 e0srr74jj) 8 nzxdqazeed in order to travel 350 km in 5.15 h?

  A runner ran the marathon (approximately 42.0 km) in 2 hours and 57 min. Whf o8 iba7hx19iat is the av1aifhb9 8x oi7erage speed of the runner in m/s?

  A car travels 90 km/h. How long dor q043+tzur,pcjp( m ees it take for it to travel 400 km?

  A ly (light year) is the distance that light travels in one year. The speed 1iyf:pt9yor 2xt3bnj m*pt61 of lig :3rpt*ytojpnf1 1 tim6b 2xy9ht 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 al3/ y0wd 0*wxl qj.aqvh-ytw( jong a straight road and you look to the side for 4.0 s, how far do x-yd/wt0whj .a(* j0l 3 yvwqqyou travel during this inattentive period?

  If you run a complete loop around an outdoor track (400 m),2szadpw) lelr tb7dhm9 9..)v b)gnw8 in 100 s, your average velocmenlsb98wd2r)9 z lpvh) ta..bw7gd)ity is

  A polar bear starts at the North Pole. It travels 1.0 km south, then sjkz hyccg 6gou3 esb9 qav55-)na 5(41.0 km east, then 1.0 km north, then 1.0 km west to return hg54jkc-aqes5)vsbo5n g( 6zyu39ac 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 travelskrlo4 ql,nb ;n9 vna,( 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 wan,v (o; knr4ll b,9nqas the bear's average velocity?

  You are driving home okl;iz 6qs)pe t gs26i0toa, z6n a weekend 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 sezs g606z;,litipq )6ot2 sakchool?

  A motorist travels 160 km at 80 km/h and 160 y qnv.zj6arak 7160sjkm at 100 km/h. What is the average speed of tjzk0167q avyjsa.6r nhe motorist for this trip?

  A motorist travels for 3.0 h at 80 km/h a+tr1hq7mt9xsw 5) acdnd 2.0 h at 100 km/h. What is her averagewxmh7sct1a)tr5 + 9dq speed for the trip?

  An airplane travels at 300 mi/h8e ns+q9 6hdbf south for 2.00 h and then at 250 mi/h north for 750 miles. What is the bdh9fqe68 + nsaverage speed for the trip?

  In a 400-m relay race the anchorman (the person who runs tj nv a5ap pk(/8qab-;pqki)h 7he 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 ck7j )h n(vaabiq/q; ppk5 a-8pan 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 13 s. The carkum5jvnt)iw0p l.5q;'s average velocity during deceleration was 78 km/h. What was the car's deceleration while sl5 pm ; uqntvj.wi0l)5kowing down?

  An airplane increases its speed from 100 m/s to bc fab: c3g9uj:ju9-y160 m/s, at the average rate of :yjcba fgjc9u39u b-:$15 \; m/s^2$. How much time does it take for the complete increase in speed?

  A car traveling 60 km/h accelerates atk p 5+sbeg1wk *-gm+gu 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 a wsyrd:fkkw8or4( w(29 ) agrvnd accelerates 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.r1rxb,c l de2y3uusde- 72+z s It then speeds up with a constant acceleration ofze dsy, 1+ 7urxu c2-brdse2l3 $2.0 \; m/s^2$ for 15 s. At the end of this time, what is its velocity?

  A cart with an initial velocity of 7.3 m/s experiences a constant accelerfi:-fwer; w k.ation ofw;.ewrffi :- k $4.7 \; m/s^2$. What is the cart's displacement during the first 6.2 s of its motion?

  A bullet moving horizontally to the right (+x z01ek3p ga 5fjdirection) with a speed of 340 m/s strikes a sandbag and penetrates a distanjzf 3pa ge01k5ce of 98.00 cm. What is the average acceleration, in $m/s^2$, of the bullet?

  A jet fighter plane is launched from a catapulte d;gar:z9fby vp.b7x8 4t81o6fg xu e on an aircraft carrier. It reaches a speed of 42 m/s at the end of the catapult, and this requires 2.0 s. e:y6zba vp1 u xr8got bf9g4xf e7d8.;Assuming the acceleration is constant, what is the length of the catapult?

  A car starting from rest movesf.z 9wl5i+zzb 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 distance of 200 m. What is its average acnj*9u6p*3zx4 ejv0 pypa 3ki vcv xak64*3pvne9 p3pzyi0u j* jeleration?

  An object starts from rest and undkuu* e76d9y 7fco)5 yjlty8b xergoes uniform acceleration. During the first second it travels 7.2 m. How far will it travel during the third b*9y uc776ul 5kfdxyeoy8j)t second?

  An object is moving y08xk. qnk h:iin a straight line with constant acceleration. Initially it is traveling at 16 m/s. Three seconds later it is traveling at 10 m/s. How far does it move during this time?k0 :x8kyihqn .

  A car starts from rest and accelerates uniformly an j5wxht zmo 43p0e5-mt $3.0 \; m/s^2$. 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 tire t ab fotf*9g;8:vkw7s-wd1jsh:j6x0aih/ mis on a dry 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 ligh.o qyn 1dh (26y9agqfde6q,s 8g.ol jqt turns green, a car that has been waiting at the intersection starts ahead with a codsonefqg1qldyqa(,89q2j o.. 6hg6ynstant 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 speed olpuq, s; :q 8wio,q8pcf 12 m/s on the surface of planet X where the acceleration due to gravity qql88pu si o,:c,;pqw 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 vf.z+o39oox r 1lpom/ surface of planet X where the accel19x.ol m3rvop oofz+/eration 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 speed of 15 mzo o.ogs3n10 y/s on the surface of planet X where the acceler 0oysnzo 3o1.gation 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 o1ro1l aeeqt 0-n the surface of planet X where the acceleration due t er lae01-ot1qo 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 friend holo:.j i7 nfdq gef.f(2zds a ruler between your fingers and releases it without warning, hzf if.7d .gnf2oe :j(qow far can you expect the ruler to fall before you catch it?

  A ball is thrown upward at a velocity of 19.6ntc-/ vnwx:n6 : 9o lip+nauh2 m/s. What is its velocity after 3.00 +:6nv2 nap9xuclw /i -noh:tns?

  A bullet shot straight up returns to its starting point in 12 s. What is thekskbk 4- s+ylwnbz58) initial speed of snz 5y8-bs+ k4k)wklbthe bullet?

  A ball is thrown straight up with a speed of 36.0 m/s. How long does it takzg1xnkg.b3tb;;7jt 2 muuvi)e to return to its starti n v;itku xzjb; .m327ugt1b)gng point?

  A ball is thrown downward from the top of a building with an initial speed pbd+,,px2 gvl of 19 m/s. It strikes the ground af, gv+xl,pdp b2ter 2.5 s. How high is the building?

  A ball is thrown straight up with (pso( nb, x(sja speed of 30 m/s. (only fill in numerical value in the blanksjson(x ,bp( (s)
(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 upvc/; z4. ih- xgixgvz. kk+v8c into the air with a speed of 36.2 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 8 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 8.0 m above the point of contact a second time.  (数值)  $s$

  In Fig. below, what is the velocity at t = *nmo m, fixoq 9q+(c;h1.0 s?

  In Fig. below, what is the velocity tx f/sg4ax9 8ycrxn1a*j wx46at t = 2.5 s?

  In Fig. below, what h9 z*j9c*enwkr dyf2 ;is the velocity at t = 4.0 s?

  In Fig. below, what is the velocity at t = 5.d/u9q nle7uwvg cgk :b5-)z/q5 s?

  In Fig. below, what is the average velocity from 0 to t--i7 ukmt5cl4.0 s?

  In Fig. below, what is the average velocity fromcprdtm7w/; u rsm,2x ( 0 to 6.0 s?

  In Fig. below, what is trsku c g.1c42-egeg0k he acceleration at 1.0 s?

  In Fig. below, what is)pf smme:ccjw 4+.n*vc9 x3ns the acceleration at 3.0 s?

  In Fig. below, what is the q( q o2s nos2shi);vx6average acceleration from 0 to 5.0 s?

  In Fig. below, what is the average acceleration from 0 to 8.0iz06xo aj,.jmg 8z*j: x7lupm s?

  In Fig. below, what is the displacement fx2mq4oz xr*t .8hu s:3ssk( hfrom 0 to 8.0 s?

Does a car speedometer measure speed, velocity? {speed|velp o vrsn *s4;ceg/6u6l+m+q yhocity}

  An object can have a varying speed if its velocity is vcogzs;zu66 2+aw ddjqx-,+ x constant.

  The velocity of an object can be nega+8l6 hs7(hcz ud+ ugunahn7p7tive when its acceleration is positive.

  If one object has a greater speed than a second obx/i0u1 bnnld /ject, the first must have a greater accelednxi1 b/ unl0/ration.

  Two cars emerge side by side from a tunnel. Car A is traveling witee p.yt;y gn9u*-9 yych 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 accelerati+o5er-z k7b s4s.chqmon decreases.

  A baseball player hitsl6k,(o yvbyupt 4 4h:61;a4kji5klqhodjg v3 a foul ball straight up into the air. It leaves the bat with a so: y h qt44u4kgb,3i6ojak vvp5lk;(yd 16 jlhpeed 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 object speeds up,1r (o 9+b4x 4qwxieoqt what is happening to its acceleration, how does ito qx1xrt+4owieq (4b9 change if air friction is ignored?

  As a freely falling object speeds up, what is happening to its accelecu,omrpqe/y1av;9s5 inh1 wi n:+l- sration, how does it change if 9 sn,-iiy5cl s1 /quranm w1pe:+vo;h air friction CAN NOT be ignored?

  An object that is thrown vel ip82n2ehol,/)fh g k*c(ce drtically upward will return to its original position with the same spdecgnpie o/ 2(hf2), lkh8lc*eed as it had initially if air resistance is negligible. If air resistance is appreciable, how will this result be altered?

  An object can have zero velocity and nonzero acceleration at the same time.ut fv.1r (uy:u.ykaf*jb qf7+

  An object can have nonzero velocity and zero acceleration+vf6) giib.g e at the same time.

  An elevator moving froww gmq/84zq j)m the second floor to the fifth floor making no stops along the way has zero acceleration all the)zqg /j4m8 qww time.

  A rolling ball moves j(s2gg-mt8jx ht;llvakf6; 8from $x_1=3.3 \mathrm{~cm}$ to $x_2=-8.3 \mathrm{~cm}$ during the time from $t_1=1.1 \mathrm{~s}$ to $t_2=5.2 \mathrm{~s}$. What is its average velocity?  (数值)  $cm/s$ (only fill in numerical value please)

  A particle at $t_1=-2.1 \mathrm{~s}$ is at $x_1=2.8 \mathrm{~cm}$ and at $t_2=3.0 \mathrm{~s}$ is at $x_2=8.4 \mathrm{~cm}$. What is its average velocity?  (数值)  $cm/s$

  A person jogs eight complny8mqu9 9,lkb 9pzqku-o1k0rete laps around a quarter-mile ($1 \; mile = 1609 \; m$) track in a total time of 12.1 min. Calculate (a) the average speed  (数值)  $m/s$ and (b) the average velocity    $m/s$

  A horse canters away from *yb r1 m6tspl-its trainer in a straight line, moving 98 m away in 11.16b1r mpt-yls* s. It then turns abruptly and gallops halfway back in 4.5 s. 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 frogseno.t,r 79se(e aj9 m $13 \; m/s$ to $24 \; m/s$ in 5.9 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 from tpg/ --gh *rne$17 \; m/s$ to rest in a distance of 71 m. What was its acceleration, assumed constant?  (数值)  $m/s^2$

  A light plane must reach a s75l40wg d 7tgd 9maajbpeed of $32 \; m/s$ for takeoff. How long a runway is needed if the (constant) acceleration is $2.9 \; m/s^2$ ?  (数值)  $m$

  A world-class sprinter can burst ox 1i qh,ar8d+(val5;pzx d, vout of the blocks to essentially top speed aboux5a d(,o hzarvp iql x8+v;1d,t $10.5 \; m/s$ in the first 14.5 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 uniformly9 8c2jfbky n;o from a speed of $20 \; m/s$ to rest in 4.66 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 high; 3ivbkox *34wlf. pljway. Assuming a deceleratio l.v4 ikwlb;3xop* jf3n of $7.00 \; m/s^2$, estimate the speed of the car just before braking.    $m/s$

  A car is behind a truck goibvcq4*n df (x*z/r3pxng $25 \; m/s$ 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 thauqyf7tu p7;hg)t( 24t ql.z+x9xsmxtn 30.0 min. After exactly 27.0 mi7 +7hz l)tqgtmxx( ut;xp9st .fu4 2qyn, there are still 1100 m to go. The runner must then accelerate at $0.20 \; m/s^2$ for how many seconds in order to achieve the desired time?    $s$