Suppose that an object travels from one point in space tpg;pj0 yv4fm 6ej vj9mty0 b3lp ,s6an 2neg1.o another. Make a comparison between the displacement and the distance4mb ; e f0.np jj0pm1e,saj2gn vy96vtl g6p3y traveled.

  When is the average velocity of an object equal to the1l m(kavw +/ni instantaneous velocity?

  A new car manufacturernc-o.av 1v od- advertises that their car can go "from zero to sixty in 8 s". This is a desccv-1vnd.- oaoription of

  An object moving in the +x axis exp w3b, nnmv),zgeriences an acceleration of $2.0 \; m/s^2$. This means the object is

  Suppose that a car traveling to the East (+x directiownbgjok9 .0o 6n) begins to slow down as it approaches a traffic lwo96 b0.jog nkight. Make a statement concerning its acceleration.

  Suppose that a car traveling to the West (-x direction) begins to slow down as id 45e0x bu cc,,qapz )crb*bk7t approaches a traffic light. Make a stat bu0b,z )d 4rca*qebx 5c,7pkcement concerning its acceleration.

  Suppose that an object is moving with a constant velocitn(00d;l +rm bysxa vq+y. Make a statement conclv;+sdx(a0mqy0r n+b erning its acceleration.

  If the velocity of an object is zero, does it mean that the accelerationl/ orb3 :wlcgj2ro4;q is zero? Support your answer with an exampler :o;3lg /24rcw bqolj.

  Can an object's velocity change direction when its acceleration is nkbr zxehx 9ozc*56; .constant? Suppox*k obcrn9 e.56 z;zxhrt your answer with an example.

  Suppose that an object is moving with co xdxlsw665dxd9 q1 )ldnstant acceleration. Make a statement conc)91dws5l6 dxdl dqx6xerning its motion with respect to time.

  Can an object have increasing speed while its accesnf v0zu4 59)keq 1bbdleration is decreasing? Support y5nd4fz1 )b uqskv9eb0our answer with an example.

  Suppose a can, after an initial kick, moves up along a smooth hill of irjg:z69)n8vp8 mbhc8 , xhgbyce. Make a statement concerning its accelerab8m:hc8rv 98 nz gjygh), b6pxtion.

  Under what condition is average velocity equal to the average of the objec*xff;afyz7 v x6v;w/dt's initial7 ;wfx6xfd *;f yavz/v and final velocity?

  Objects A and B both start at rest. They both accelerate at1) s5qb8l botk the same rate. However, object A accelerates for twice the time as object B. What is the final speed of object A compared to that of obje 5o)1bq8kbsltct B?

  Objects A and B both start from rm8q zm/cct* o)est. They both accelerate at the same rate. However, object A accelerates for twice the time as object B. What is the distance traveled by object A compared to that of object /8oqtm z)cm*cB?

  When an object is released from rest an bj/ nt6)oq,fxd falls in the absence of friction, which of the following is true concerni )/,6tqb fonxjng its motion?

  When an object is releasx6v4lg601f yog3uismk4frbe l ;7m1fed from rest and falls in the absence of friction, which of the following is trusg4 1iu01er76kffmvgx3fmlb l ;oy46 e concerning its motion?

  Suppose a ball is thrown straight up. Make a zgk18- qap( ok statement about the velocity and the acceleration when the ball reaches th1ak(o8g-zqk p e highest point.

  Suppose a ball is thrown straight up. What *v kv1qddgj/b6l; 7et is its acceleration just before it reaches its h;btqel/d 17v kv 6dgj*ighest point?

  Suppose a ball is thrown straight up, reachetgc++/g cz+ dds a maximum height, then falls to its initial height. Make a statement about the direction of the velocgddccg+z/ + t+ity and acceleration as the ball is going up.

  A ball is thrown straight up, reaches a maximum height, then falls to itjll9/4wlrzl1 mxwa52:p : bb cs initial height. Make a statement about the direction of the velocity and accelerawb9b z21lr:cj/x45mw:l ll aption as the ball is coming down.

  Suppose a ball is thrown downward in the absence of air resistance. Make aiitb9brkzweca6 ) 9 k- q-g6sm( )opm) statement concerning itszb) ck m996) k6)q oir(bsgit-ewmp -a acceleration.

  Suppose a skydiver jumps from a 3w nll8 j:hu 9yi.rle:high-flying plane. What is her acceleration when she she reac9:yell lhi.jr un:8w3hes terminal velocity?

  A ball is thrown vertically upward with a speed v. An identical second ballo,8z(7wolhn8u1ef1:s2+ j vbqi tge c is thrown upward with a speed 2v (twice as fast). What is the ratio of the maximum height of the second ball to thasj172 ozgn+lv ih(toqc,1f8e:ewb 8u t of the first ball? (How many times higher does the second ball go than the first ball?)

  Ball A is dropped from the top of a buildinrkr4cva3av ejj,;) 2cg. One second later, ball B is dropped from the same building. As time progresses, the distance between thjj2a) ;crv,a vk 43cerem

  Ball A is dropped from th61i,ifis6m.b 4wjsy be top of a building. One second later, ball B is dropped from the same building. As time progresses, the difference in their . wj,i 6 f6sym41ibibsspeeds

  Two objects are thrown from the tamdg vby1 8a6,r ht)r+op of a tall building. One is thrown up, and the other is thrown down, bot1b ),8ry+gdth amv6ra h with the same initial speed. What are their speeds when they hit the street?

  A brick is dropped from the top of a building. A second brick is throwyb 5 sjeh k8na(.do:s/n straight down from the same building. They are released at the same time. Neglect air resa(5/ o:dyj8khe sb. snistance. Compare the accelerations of the two bricks.

  An object is moving with constant non*09cazv;yfl. +zrlua-zero velocity in the +x axis. The position versus time graph of this object isz 0clyalvfua* ;9zr .+

  An object is moving with constant non-i./grgj2ig f 6gps9/n 67zzzbzero acceleration in the +x axis. The position versus t/z gs9i/6g7g z2g rzj f.b6pniime graph of this object is

  An object is moving with crw* cut4qz: e/onstant non-zero velocity in the +x axis. The velocity versus time graph of this ob4zrctqe w */u:ject is

  An object is moving with constant non-zero accelerati*yrsgj 7ih3s 4on in the +x axis. The velocity versus time graph ofjiygr 4s 73sh* this object is

  The slope of a position versus time graph gkvvc 34ygcjjj.i:2.z e, n. smives

  The slope of a velocity versus time graphjgv2o(73 sf(pce nkb3 gives

  The area under a curve in an acceja7*cuk ny3*d;k+fh p ay 9k-yleration versus time graph gives

  The area under a curve in a velocity versus time graph8lje5g +6 ruzu gives

  If the position versus time graph of an object 7alvt-y c: 1nct6gt :6p,gubf2a wou2 is a horizontal line, the object isgu au ,cf -7wt 2lt6 on:g2a1b6cp:yvt

  If the position versus time graph of an object is a verticalo 1bnttkg(ir2,* 2c bsuf )+yl line, the object is * u2bt,2 (ygicko)fntbslr+1

  If the velocity versus tim+.gz v26jh-j/jp zodr e graph of an object is a horizontal line, the object is6j vzzrhg /d+op-j.j2

  If the velocity versus t2 vqs.2kp+ jllime graph of an object is a straight line making an angle of 30 degrees with the ti2q lk +2pvsl.jme axis, the object is

  An object moves 15.0 m north and then 11.0 m south. Fi36 y:5 q6yow acfl7wkk; w6np97w bnpknd both the distance traveled and the magni kwoa;6pnfw63wpqck5 n6blw k : 97yy7tude of the displacement vector.

  A boat can move at 30 km/h i4u 394 pias8mbh*,dv o/ezwxuw6 /dqon still water. How long will it take to move 12 km upstr 4qbzs, o43oidhwxumd v6p89/au/we *eam in a river flowing 6.0 km/h?

  55 mi/h is how many m/s? (1 zr6 ,yq3mix9p mi = 1609 m)

  What must be your average speed in ord:fvbo*hvb)x7e s. 1 hoer to travel 350 km in 5.15 h?

  A runner ran the marathon (approximately 42.0 km) in 2 hours xi .3o(on8zgzand 57 min. What is the average speed of the runnno .8zi3 ogzx(er in m/s?

  A car travels 90 km/h. How long does it take for it to travel 400 kmov) nel*b)-7l)+ 0saeouiykj ?

  A ly (light year) is t.swr2 wvk77 (o/jb zkbhe distance that light travels in one year. The speed of light b kv7.kw (j/s2w7o rbzis $3.00 \times 10^8 \; m/s$. 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 lookmwl+ ,wop ju 9dx5 e( /*3b5cdn1rexav((ipvv to the side for 4.0 s, how far do you travel duringd,ow+rvj*ep/mxliav(u dx95(ce13nw ( bvp 5 this inattentive period?

  If you run a complete loop around an outdoor track (400 m), in 100 s, y r-dd)nd- 2dxsour average veloci-)n2drd ds-xdty is

  A polar bear starts at the North Pole. It travel9( 5nhupxvmp2t r8s*hs 1.0 km south, then 1.0 km east, then 1.0 km north, then 1.0 km west to return to its startinmth 9s8pprnh* (5x2vug point. This trip takes 45 min. What was the bear's average speed?

  A polar bear starts atxl)xrlts3m:atzit m 5.8 ) zc5 the North Pole. It 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)x. :tx8m zct5am)3si lzr5tl velocity?

  You are driving home on a weekend from school at 55 mi/h for 110 milesdj* he6e,( r vili;us.. It then starts to snow and you slow to 35 mi/h. You arrive home afi(ju,. er*vel;6dhis ter driving 4 hours and 15 minutes. How far is your hometown from school?

  A motorist travels 160 km at 80 km/h and 160 km at 100 km/h. What is b7gbewb;o(4t9 6tq +ew 7eqlw sgu()h the average speed of the motorist q+7 glw bw9wg6u ht4boe7t)e e(qs(;bfor this trip?

  A motorist travels for 3.0 h97tv: b bpvhy7 at 80 km/h and 2.0 h at 100 km/h. What is her average speedvt79 yb hv:7pb for the trip?

  An airplane travels at 300 mi/h south for 2.00 h and p nob6s eyop.c; :(w)sthen at 250 mi/h north for 750 miles. What is cy;boe6snp (w. o:s)p the average speed for the trip?

  In a 400-m relay race the anchorman (the person who runs the last 10zqp 47:eing; (gr 1o,dq9vxvb0 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 the final leg of the race, in order that the team A runner not lose the qreivgq;,dnx( g pob 49v71z:race?

  A car decelerates uniformly and comesio l(k2q0o vsro51kyj h/kvqd,o 6)e9 to a stop after 11 s. The car's average velocity during deceleration was 32 km/h. Whjsyko,lkvd 9/qo2r k h 6(v)0e 15qiooat was the car's deceleration while slowing down?

  An airplane increases its speed from 100 m/s to 160 m/s, atnlq 1w83f)wulr 9pc; x the average rate of qn r 8lc19fpw x3l;wu)$15 \; m/s^2$. How much time does it take for the complete increase in speed?

  A car traveling 60 km/h accelerates at ufb+m7b;nl.l6f;m w vh/ 3io xthe 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* ;v( gh(r8zcbs2 +ka*e snpyond 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. It then u)h0sbjko45q /gog)we7ttm , speeds up with a constant accelerationkgs ogh0/q)mj,b uo7)t w 5te4 of $2.0 \; m/s^2$ for 15 s. At the end of this time, what is its velocity?

  A cart with an initial velocity9p2ggyt w 3*k pu5bfy4 of 1.3 m/s experiences a constant acceleration ofpbpwgy kf4t 5u y932*g $2.8 \; m/s^2$. What is the cart's displacement during the first 5.3 s of its motion?

  A bullet moving horizontally to the right (+x direction) with a spee-brf9-p)gtvn d of 579 m/s strikes a sandbag and penetrates a distance of 88.52 cm. What is the average acg-ntfv p b-9r)celeration, in $m/s^2$, of the bullet?

  A jet fighter plane is launched from 9,kl6 r7gf u.rhar 6we-8fg cya catapult on an aircraft carrier. It reaches a speed of 42 m/s at the end of the catapult, and this requires 2.0 s. Assuming the acceleration is constant, what c r kr-69u 7.arweghf gf,l6y8is the length of the catapult?

  A car starting from rest movetsw hpeh2ig+5)t,6 jj s 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 ni7:3hqcb4f:8 a k gzkaverage acceleratknfzckg8:h4b:7 i3 qaion?

  An object starts from rest and undergoes uniform acceleration. During the p;z dd*4ancek 7 b-2.jlrc6usfirst s 4b .*j-6ld7cke;zc upsrda2n econd it travels 1.4 m. How far will it travel during the third second?

  An object is moving in a straight line with constant acceleration. Initiaf36jeo1 l0zuhlly it is traveling at 16 m/s. Three seconds later it is traveling at 10 m/s. Ho3z0 jf hu1leo6w far does it move during this time?

  A car starts from rest and accelerates uniformly at7*dzlh(u,7.jqck wb2c d6 dv s $3.0 \; m/s^2$. 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 decelerate at + ;jy swvyq-ty(:7urbw7 1vj(q6 cbphabout $5.0 \; m/s^2$ 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 been waitiq;ui.dz 89qo).m gch tng at the intersection startu8 co md9;) qiq.hz.gts 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 upwardtkxib/ 6mjc9b m j4*b9 with a speed of 12 m/s on the surface of planet X where the acceleration due to gravity imc9j9/b * jtkimbx4b 6s $1.5 \; m/s^2$. What is the maximum height reached by the object?

  An object is thrown upward with a speed of 12 m/s on the surface of2rxdef1u4u 7/nr j:v2:qixvu planet X where the acceleration due to gravity :4jrdu2nu12q/fvr7i evx: uxis $1.5 \; m/s^2$. How long does it take for the object to reach the maximum height?

  An object is thrown upward with a00aj j1ueniro3 wgtrxep/v 22mo :0d3 speed of 15 m/s on the surface of planet X where th0v0oog22den0tx:3e /3aw1pm iujrj r e acceleration 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 prm8 a xpjo;bs-t63 w39i zncuna2 3mj ,jvbe11lanet X where the acceleration due to o3b81aj ia xm93 jv zrncn1 ,spj-umte 2wb;63gravity 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 holds a rult,yoke* ;w:frt r;+rr er between your fingers and releases it without warning, how far can you expect the ruler to fall before you catro:t,r k+r*erf;y;wtch it?

  A ball is thrown upward at a-5op +hyvaq j; velocity of 19.6 m/s. What is its velocity after 3.-a+ 5hqjpv;oy 00 s?

  A bullet shot straight u10jez-*x be;jujpkt y)1-2wsu ot+wup returns to its starting point in 10 s. What is the initial sxyu wk;ts-)2 ojtujezw 1+ b*jpu 1-e0peed of the bullet?

  A ball is thrown straight up with a speed of 36.0 m,hpgmg a m5-/t/s. How long does it take to ret g5/mt,pg- hmaurn to its starting point?

  A ball is thrown downward from the top of a building with anm he17m 0q a8cysg9h6kyw12bc41c zwl initial speed of 15 m/s. It strikes the ground after 1.0 s. How hi cch4c emb2qy1k0gwm6sy1h z 81w7al9gh is the building?

  A ball is thrown straight up with a speed of 30 dr(yk3dun)3f2ie ghku;.8fx 8zkhr8 m/s. (only fill in numerical value in the blanki8338kdnrukufgkerf(8 x;2 )hdzyh.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 up into theofjrut,4/p;rx9(. f ztob,. sfnu,e v air with a speed of 20.1 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 11 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 11.0 m above the point of contact a second time.  (数值)  $s$

  In Fig. below, what is the veloci2 g yqo8.oebpque7q 84ty at t = 1.0 s?

  In Fig. below, what is the vel3sz55koe2ycrys 0t3r . jc;t1w:uva yocity at t = 2.5 s?

  In Fig. below, what is the velocity at q2i3.4e7-v pya /p* adnhgf: yvrkifvk1u s49t = 4.0 s?

  In Fig. below, what is the velocity at t = s+/ )jeug (qxr5.5 s?

  In Fig. below, what is the p5qor fh0-wm- j 6g+knaverage velocity from 0 to 4.0 s?

  In Fig. below, what is the average veqf4 b)ch15nerc/ntvnev a.8 6locity from 0 to 6.0 s?

  In Fig. below, what qy13f30j0r g b.w 5gwbhjgf 4fis the acceleration at 1.0 s?

  In Fig. below, what is the accejs:-i6wi *q2 x9uu mztleration at 3.0 s?

  In Fig. below, what is the average acceleratiort:yw8l v /*n:s kchl57gaug ;n from 0 to 5.0 s?

  In Fig. below, what is;wri2qn qg4q 0 the average acceleration from 0 to 8.0 s?

  In Fig. below, what is the displacement cp ,wk80qt9 qefrom 0 to 8.0 s?

Does a car speedometer measure speed, velojt)h oy5r/yaon3 5 l8icity? {speed|velocity}

  An object can have a varying speed if its vel,d)jbvh v,aa0 /u7ksz ocity is constant.

  The velocity of an object can be negative when its accelerin 7i xuh*bn4ycqrye1o8n*(8 ku i;e (ation is positive.

  If one object has a greater speed than a second object, the first mu 3kj/4p(rva1s)(:zy1qny :j d0b6rc ex fksbwst have a grfp((0jzd :1 31b rcskvy 6/r b nsxw)jeq4yka:eater acceleration.

  Two cars emerge side by u7 boge0i*ggw7nh;p;side from a 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 accelet1 k, *79sqr.uhk aiylration decreases.

  A baseball player hits a foul ball straight up into thi qx0wyoh*mx(6 g +;tje air. It leaves the bat with a speed oq0wxi*6 xy(+o tmhgj;f $120 \; km/h$. 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 happening to its acceleration, ho +,lj-dy +6xmvd qosf0w does it co+sljm,+ y6 xdf0d q-vhange if air friction is ignored?

  As a freely falling object hf2 ay5r (pn0rspeeds up, what is happening to its acceleration, how does it change if air friction CAN NOTfnry 0hp(a2r 5 be ignored?

  An object that is thrown vertically upward will return to its originalai3vx/ d72/ k u2w tikcpqp.2 6slgt5a position with the xgs p26ki cdt2 a/ipvl a.3qu572/wtksame speed 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 th* xu7a0f4yt 0 :oh*fwu dzuz9je same time.

  An object can have nonzerowo 5s1mv6uhe1yi9( e+ae+ t gf velocity and zero acceleration at the same time.

  An elevator moving from the second floor to the 0d-gk3k*hbdl*z0bsn 6m g /sosqe1 t)fifth floor making no stops along the way hasshb0 mb 0qkt *s1)kgn3 -6/dsgdzol* e zero acceleration all the time.

  A rolling ball moves -e sl0 kx;z3aw2d:o-rrgv;o vfrom $x_1=2.0 \mathrm{~cm}$ to $x_2=-8.1 \mathrm{~cm}$ during the time from $t_1=2.5 \mathrm{~s}$ to $t_2=5.8 \mathrm{~s}$. What is its average velocity?  (数值)  $cm/s$ (only fill in numerical value please)

  A particle at $t_1=-3.9 \mathrm{~s}$ is at $x_1=2.8 \mathrm{~cm}$ and at $t_2=4.0 \mathrm{~s}$ is at $x_2=7.9 \mathrm{~cm}$. What is its average velocity?  (数值)  $cm/s$

  A person jogs eight complete lapsu/mpr5rt7-1 rnm m/ek around a quarter-mile ($1 \; mile = 1609 \; m$) track in a total time of 9.6 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 stragjzzs 1* )2lzeight line, moving 99 m away in 13.9 s. It then turns abrs e zz*g1l)2jzuptly and gallops halfway back in 4.6 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 froumo t(: e 4myho5+8loj(ubw exv5( 8nzm $10 \; m/s$ to $23 \; m/s$ in 4.2 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 p :w .3l;rjtmw$16 \; m/s$ to rest in a distance of 59 m. What was its acceleration, assumed constant?  (数值)  $m/s^2$

  A light plane must redb+bz+3r k(yn *dnjp4 ach a speed of $29 \; m/s$ for takeoff. How long a runway is needed if the (constant) acceleration is $2.8 \; m/s^2$ ?  (数值)  $m$

  A world-class sprinter can burst out of the blocks to essen9.. m aonwasmgs/h : mah4d6 (p5t9ffidm*6eqtially top speed aboutfh9h am pm64as(g5d oa:n 6.*swf dmti.qe9 /m $10.1 \; m/s$ in the first 13.1 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 uni249u w5e3h vnvf u,jtqformly from a speed of $19 \; m/s$ to rest in 4.13 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 thei5 kg;jwc+i2v+r( zwn highway. Assuming a deceleratioik+zv;ic+rw 5(ngw2 jn of $7.00 \; m/s^2$, estimate the speed of the car just before braking.    $m/s$

  A car is behind a truzf8v q1um29v gck 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 5unfn81a0 j6c ;0 rytsuez:g hless than 30.0 min. After exactly 27.0 min, there are still 1ngca865ey usn:zur tj fh 100;100 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?    $s$