Which of Newton's lawa2ji5 (q *niugs best explains why motorists should buckle-up?

  When you sit on a chair, the resultanta(/4- feojgm xpr q 0qgx6y/xhapk5)- force on you is

  In the absence of an external force, a mov y(2(c) yu nty6akb3na1n kr;ling object will

  When the rocket engines on the starship NO-PAIN-NO ;2r4nm/itdq48oeqj o-GAIN are suddenly turned off, while travelij 42rnd8o 4oemqiq;t/ng in empty space, the starship will

  A rocket moves through empty space in a straight line with constant speeaz-vh g(*4xyg d. It is far from the gravitational effect of any star or planet. Under these conditions, the force that must be applied to the rocket in order to sustai-*hgva z yx(g4n its motion is

  You are standing in a moving bus, facing forward, and you suddeds*z, ); tqtjdnly fall forward. You can imp*t sjzd ,t;qd)ly from this that the bus's

  You are standing in a moving bus, facing forward, 4gkb5p-hh;e,6 v ncnaand you suddenly fall forward as the bus comes to an immediate stop. What force ca 6a4n k,g 5h;evhpc-bnused you to fall forward?

  A constant net force acts on an object. Describe the motion oj:lxu8rlb9y2 g uq53g8f x3op f the object.

  The acceleration of anfog(7i: 6t/ mai9og k ya.xp0wqic*+w7(bf ay object is inversely proportional to

  A net force F acceleratehij txm0g+e p5ktg-: 8e/v-jas a mass m with an acceleration a. If the same net force is applied to mass pj5v etejigth0a-g8k m-+/x : 2m, then the acceleration will be

  A net force F acts on a mass m and produces an a6fr:v3t)r 87 uqfu lgocceleration a. What acceleration results if a net force 2F aoffgul:68)r tur q 37vcts on mass 4m?

  If you blow up a balloon, and then release it, the balloon will fly aec5r ea+(km d2way. This is an 5e m( r2deac+killustration of

  Two cars collide head-on. At every moment dus)rtv4/j9iyya dc*n hd* 451 d ltz+fbring the collision, the magnitude of the force the first car exerts on the second is exactly eyt*d1yalf bdhi 49cs/ vt )nj 5rz*d+4qual to the magnitude of the force the second car exerts on the first. This is an example of

  If you exert a force F on an object, the for8hkf26lhks ;x0k jf*-q, gxcyce which the object exerts on you wilgy*8sl -h2kfqc;kh, f60 jxxkl

  Action-reaction forctylr :-4 wld:86 iqhcbes

  Action-reaction forces are1y5h(x) jp lv:pecg o9

  A 20-ton truck collides with a 1500-lb car and causes a lot of damage 87kc4d flbf 6y(*j dh(kkcq7r to the car. Since a lot of damage is dy jl7bk*q(f(d8fd h k7c6k4rc one on the car

  An object of mass m sits on a i78 s 8yhf4gaqebh a2is75bp)flat table. The Earth pulls on this object with force hbg4)77bqefissi8a8pa y5h 2mg, which we will call the action force. What is the reaction force?

  A child's toy is suspende0t kss6,pvw *o 1sxlz0 7sc1w9ypjw0zd from the ceiling by means of a string. The Earth pulls downward on the toy with its weight force of 8.0 N. If this is the "actix6svpwj0kw s,pt* 9 slw107szc1zo 0yon force," what is the "reaction force"?

  Your bat hits the ball pitched to you with a 1500-N inscsf /g86t-s9zkwov+btantaneous force. The ball hits the bat with an instantaneous fo8+ z6o bts-fv /ws9ckgrce, whose magnitude is

State Newton's three b t0c osfu5-rg8h(i7 glaws.

  Mass and weight

  The acceleration due to gravity is lower on the Moon thsk1d ,wyokbf9m;ro) + an on Earth. Which of the following is trs;1m,koo)f bdr ykw+9ue about the mass and weight of an astronaut on the Moon's surface, compared to Earth?

  An example of a force which acts at a distance isajmt f( )so8. s;tqz*c

  Who has a greater weight to mass ratio, a person weigaz+o. mkn8om)4 fvp b3hing 400 N or a person weighing 600 Nnv+p38oo)bmfm4 az k.?

  A stone is thrown straight up. At the top of its path,bqamh4xy9 ba4wo8/a( the net force acting on it isa/ mw4x9y4o8a qabb(h

  A 20-N weight and a 5.0-N weight are dropped simultaneouslye mel- h6oki(,p w)(yl from the same height. Ignore air resistance. ym(hi-(),w el6klepo Compare their accelerations.

  A brick and a feather fall to the jy:xp9/slad6 y v *d:zearth at their respective terminal velocities. *z :v6lad/jsxpy:yd9 Which object experiences the greater force of air friction?

  An object of mass m is hanging by a strin a zz6y5 w;wwmd:(65htloa3 pcg from the ceiling of an elevator. The elevator z tow aa 6py(hz;56m3cd5w:wlis moving up at constant speed. What is the tension in the string?

  An object of mass m is hanging b2w05b46jo d-asrx nopy a string from the ceiling of an elevator. The elevator is moving upward, but slowing down. Whjr w-db24opx 5 0n6osaat is the tension in the string?

  The force that keeps you from sliding on anl*3ci,wk 2nkq icy sidewalk is

  It's more difficult to start moving a heavy carton from rest than it is to keenoxf, +.s6mltp pushing it with c+,lnso. mtf6xonstant velocity, because

  A horizontal force accelerates a box from rest across a horizontal sgv(9r:1 p gs)y+mlyby8n txp: urface (friction is present) at a constant rate. The experiment is repeated, and all conditions remain the same with the exception that the horizontal force is doubled. What hapvgxpb:y )l n rp8y(:t+m9 gsy1pens to the box's acceleration?

  A packing crate slides down an incl6j2o1wwo 6t)v7 n6gyyfgh s +dined ramp at constant velocity. Thus we can deduce thg v 6yy2nhgwj 7+ods)166 owftat

  A block of mass M slides down a frictionless plane inclined at an n7i hlh zp6k0*angle q with the horizontal. The normal reaction force exerted by the plane on the b n l06phhiz7k*lock is

  A block of mass M slides down a frictionless plane inclined at an angle q with s,ppb1wbu un1rvx-av 6 6k +j4uj/tt1 the horizontal. Tprt1nau t1 6x ksbj /4 bw,-1+p6juvuvhe normal reaction force exerted by the plane on the block is directed

  A block of mass M slides down a friction8h,:bl, whdb xless plane inclined at an angle q with the horizontal. The gravitational fob 8,hhxl,db:w rce is directed

  Two toy cars (16 kg zht i6enr(b ek3)7j0hand 2.0 kg) are released simultaneously on an inclined plane that makes an angle of 30e with the j0ztkine37h(r 6bh e)horizontal. Make a statement which best describes their acceleration after being released.

  An object sits on a fricti260 jxu nwbvj(onless surface. A 16-N force is applied to the object, and it acceleraxjv62(uwjb 0 ntes at $2.0 \; m/s^2$. What is the mass of the object?

  A sports car of mass 1000 kg can accelerate from rest to 27 m/s i 16cb(hpc1r 5iqbd ,gcn 7.0 s. What is the avera rp1d5ic,1b (ccqgb6 hge forward force on the car?

  Starting from rest, a 4.0-kg body reaches j1 ulr+:8+twmhjp z;v a speed of 8.0 m/s in 2.0 s. What is :jluvt+p w+r8 ;h1jmzthe net force acting on the body?

  An antitank weapon fires a 3.00-kg rocket which acquires a speed of 50.0 (m r;t+yte yvql)h9t9m/s after travthm)tl+ ye rtv(qy99;eling
90.0 cm down a launching tube. Assuming the rocket was accelerated uniformly, what is the average force acted on it?

  If you push a 4.0-kg mass with the same force that you push a 10-kg mass from s)tr4dh(wwe3 res3w)th(ds wre4t,

  What is the mass of a person w6i n.7pi/hhv)b 2e nyaj ea9(sho weighs 110 lb?

  What is the mass of an object that 7 cm(2i5c1ejr 4a-lv kjkn,riweighs 250 N on the surface of the Earth where the 5rjeal,m i 7 -42cc(i1vkrjnkacceleration due to gravity is $9.80 \; m/s^2$?

  An object has a mass of 60 kg on the Earth. What is theaa4.qbg - 211izvn wfd mass of the object on the surface of the Moon where the acceleration due to gravity is only 1/6 of that on zv.fani -w11bdq24ag the Earth?

  Object A weighs 40 N on Earth, and object B weighs 40 N onzyv w+ f.04aai the Moon. The Moon's gravityi .azwa40v+f y is one sixth of Earth's. Compare the masses of the objects.

  Sue and Sean are having a tug-of-war by pulling on opposite ends of a 5.0-kg r( z)snjx 2kjv g1)s3rjop( grsv1 s)23zjkx)jjne. Sue pulls with a 15-N force. What is Sean's force if the rope accelerates toward Sue at $2.0 \; m/s^2$?

  A stack of books rests on a level frictionless surfacegq r0kp4m 7mw2. A force F acts on the stack, agm0k q rwm247pnd it accelerates at $3.0 \; m/s^2$. A 1.0 kg book is then added to the stack. The same force is applied, and now the stack accelerates at $2.0 \; m/s^2$. What was the mass of the original stack?

  A person of weight 480 N stanyly/qq6ghjuy2j+c a,z r,:: uds on a scale in an elevator. What will the scale be reading when the elevator is accelerating downway:2gchuj:j6 zql/,u arq+ yy,rd at $4.00 \; m/s^2$?

  A person on a scale rides in an elevator. If the ma p;,e0ixd g*q.dgefe0ss of the person is 60.0 kg and the elevator accelerates downward with an acceler .i*pe;,0dedggf 0xqe ation of $4.90 \; m/s^2$, what is the reading on the scale?

  A person on a scale rides in an elevator. If the mass off5c2kjbe*qtjve 3xh/fy(l (7 the person is 60.0 kg and the elevator av2c7 tk * 3l/bqyxjjehf(f5e(ccelerates upward with an acceleration of $4.90 \; m/s^2$, what is the reading on the scale?

  Two horizontal forces act on a 5.0-kg mass. One4jm7vp ; kyp xsgs9 h7kf-;0s 5tms(0-olc koq force has a magnitude of 8.0 N and is directed due north. The second force toward the east has a magnitude of 6.0 N. Wtg -0 k 0hvo4 mpf;lsyp(- sokj9;5x7q sskcm7hat is the acceleration of the mass?

  An object of mass 6000 kg rests on the flatbed of a truck. It is heu/be zgq r;5v/ld in place by metal brackets that can exert a maximum horizontal force of 9000 N. When the truck is traveling 15 m/s, what is the minimum stopping distance if the load vgqz//;r be 5uis not to slide forward into the cab?

  An object of mass 6000 k .a 9af9)lwixp8m +ycvzw2de+g rests on the flatbed of a truck. It is held in place by metal brackets that can exert a maximum horizontal fo vczdma2 9a.9iefxp8 ylw w+)+rce of 9000 N. When the truck is traveling 15 m/s, what is the minimum stopping time if the load is not to slide forward into the cab?

  In the Atwood machine shown in Fig. 4-1, if M = 0.60 6:0f3fbha.r ge)keqakg and m = 0.40 kg, what is the magnitude of the acceleration of the system? (Ignore friction and the massf: a gqk .0br3e)afh6e of the pulley.)

  In the Atwood machine shown in Fig. 4-1, if pv4lx5w: ro6 rwggv68 M = 0.60 kg and m = 0.40 kg, what is the ten gxg6 wvo6rw:pl8v45rsion in the string? (Ignore friction and the mass of the pulley.)

  A student pulls a box of books on a an.2pkzeghwp--: wrs59d:e3 v uv a.ysmooth horizontal floor with a force of 100 N in a directionnv. a2av u5 .sgrw-k93 w:de-z:ep yph of $37^{\circ}$ above the horizontal. If the mass of the box and the books is 40.0 kg, what is the acceleration of the box?

  A student pulls a box w-d : f7sogwj35g wzi(1jr v+bof books on a smooth horizontal floor with a force of 100 N in a direction of 37.0e above the horizontal. If the mass of the box and the books is 40.0 sw1gwbv(j57:jg r3do +w zfi- kg, what is the normal force on the box?

  A traffic light of weight 100 N is supported by two ropes as shown in Fpv6a+ 8hge*;jta3do f aggs:;ig. 4-2. What are the tensions in thgf dt6 ;+8vgs;:jaehg3poa*ae ropes?

  In Fig. 4-2, if the tensions in the ropes are 50 N, what ibezf,cqm2i n0c02n6 -eden+hs the mass of the traffic light0 2ce 2bizfqmh c6 ,-d+ne0nne?

  Two boxes of masses m and 2m are ivhk9 *t;+s4xrg2qg epn contact with each other on a frictionless surface. (See Fig. 4-3.) What is the acceleration of the more m qe ;h r+sv2p*xk4g9tgassive box?

  Two boxes of masses m and 2m are in con*a.z 4 iad-qgqtact with each other on a frictionless surface. (See Fig. 4-3.) What is the net force on *- gqaaidq4.z the more massive box?

  Two boxes of masses m and 2m are connected by a rope. (See Fig.r+e)bl y v 5noh e cjyb3x*k3-;7nu1fq 4-4.) If the forward force on the more massive box is F, what is the tens rf ;+jevkx 1n*yyu b3ch3 )-qoeln57bion in the connecting rope?

  Two boxes of masses m and 2m are connected y*i4kl7eu ky 4es .b)nby a rope. (See Fig. 4-4.) If the forward force on the more massive box is F, what is yl )kbyin.*u ee7k 44sthe acceleration of the less massive box?

Two boxes are connected by a cord running over a pulley as sh pel+4 (7fuhpsown in Fig. 4-5. Box f eul+7(ph ps4I of mass
8.0 kg rest on the top of the table; the coefficient of kinetic friction between box I and the table is 0.10. Box II has a mass of 15.0 kg.
(a) Draw the free-body diagrams for the two boxes, identifying all of the forces acting on each of the masses.
(b) Calculate the acceleration of the system.
(c) Calculate the tension in the cord.

  The coefficient of stt *8pcj 3k:bohatic and kinetic frictions between a 3.0-kg box and a desk are 0.40 and 0.30, respectively. What is the net force on the box whpcb:oj3 k*8then a 15 N horizontal force is applied to the box?

  The coefficients of static and kinetic frictiogbt,n2. zmsg: ns for plastic on wood are 0.50 and 0.ts.2 n,gzb:gm40,
respectively. How much horizontal force would you need to apply to a 3.0 N plastic calculator to start it moving from rest?

  An object slides on a level surface in the +x direction. Iipxc h. m;tps--3,ro pt slows and comes to a stop with a constant accelerationtp-h3p ,s. cimxor;-p of -$2.45 \; m/s^2$. What is the coefficient of kinetic friction between the object and the floor?

  A 10-kg box sitting on a horizontal surface is pulled by a 5.0-N force. A 3.0-rqocs9 f537 gs s3ncky0h)-moN friction fn3ck9y rqs- g07om3c) o5 shsforce retards the motion. What is the acceleration of the object?

  A horizontal force of 5.0 N accelerates a 4d6 e4 ic.2six7mtqjh* .0-kg mass, from rest, at a rate of $0.50 \; m/s^2$ in the positive direction. What friction force acts on the mass?

  During a hockey game, a puck is given an initial speed of 10 m/s.wht;. pgj/s-e It slides 50 m on the ice before it stops. What is the coefficient of kinetic friction between the puck aw .p j;g/-htsend the ice?

  During the investigation of a traffic accident,fbl4t yg w2-x7foq11c police find skid marks 90.0 m long. They determine the coefficient of friction between thyb 1fl-g wt42fc17qxoe car's tires and the roadway to be 0.500 for the prevailing conditions. Estimate the speed of the car when the brakes were applied.

  Two boxes of masses m and 3m are stacked. (See Fig. 4-6.) The surfacek .p w2el(w:q;2tvuty between the more massive box and the horizontal surface is smooth and the surface between the boxes is rough. If the less massive box does not slide on the :wyu .tq2tp2(vkw;le more massive box, what is the static friction force on the less massive box?

  Two boxes of masses m and 3m are stacked. (See ftml- hc)3- zyt* 1dpqFig. 4-6.) The surface between the more massive box and the horizontal surface is smooth and the surface between the boxes is rough. If the less massive box does not slide on the more massive box, what z- hy-q mtc)1td*flp3 is the coefficient of static friction between the boxes?

  An object is on a frictionless inclined plane. T5ml/l ( kw1pihtz: t9jhe plane is inclined at an angle p/l:(jtm1 litw9z k5h of $30^{\circ}$ with the horizontal. What is the object's acceleration?

  A 10-kg mass slides down a flat hill that makes an angle of embdytwwj;(ca-k5 10 $10^{\circ}$ with the horizontal. If friction is negligible, what is the resultant force on the sled?

  A mass is placed on a smooth inc..ogig d- e 9an6fw0xllined plane with an angle of $37^{\circ}$ to the horizontal. If the inclined plane is 5.0-m long, how long does it take for the mass to reach the bottom of the inclined plane after it is released from rest?

A block lies on a smooth inclined plane tiltewf- wabtx )sle fgw82:9/;s lrd at an angle of $35^{\circ}$ to the horizontal.
(a) Draw the free-body diagram for the block.
(b) Determine the block's acceleration as it slides down the inclined plane.
(c) If the block started from rest 8.5 m up the incline from its base, determine the block's speed when it reaches the bottom of the incline.
(d) How long did it take the block to reach the bottom of the inclined plane?

  A wooden block slides directly down an inclined plane, at m2*. jt(o xoj-nrl + m;nbtgj0a constant velocity of 6.0 mxm- 2*r ;0btj gtnmnjj( +ol.o/s.
What is the coefficient of kinetic friction, if the plane makes an angle of $25^{\circ}$ with the horizontal?

  An object with a mass m slidek7-7xwjlqxckj-f-8ip klet8 ..gp) fs down a rough $37^{\circ}$ inclined plane where the coefficient of kinetic friction is 0.20. What is the acceleration of the object?

  An object with a mass m slides down a roughze nwusz /t)(hilt tx8/.4:nv+ zuv;c $37^{\circ}$ inclined plane where the coefficient of kinetic friction is 0.20. If the plane is 10 m long and the mass starts from rest, what will be its speed at the bottom of the plane?

  A bulldozer drags a log weighinu 1;g+y*s5,xbmuquu rg 500 N along a rough surface. The cable attached to the log makes an b qgxu mur1yu*;su+5,angle of $30.0^{\circ}$ with the ground. The coefficient of static friction between the log and the ground is 0.500. What minimum tension is required in the cable in order for the log to begin to move?

A 25.0-kg box is released from.k2npny)2cq1oqc j,gf : o pnyx.7 8iv rest on a rough inclined plane tilted at an angleq. cx2:8 o)pj,nnnq2ygkpvy 7 c i1f.o of $33.5^{\circ}$ to the horizontal. The coefficient of kinetic friction between the box and the inclined plane is 0.200.
(a) Draw the free-body diagram for the box.
(b) Determine the force of kinetic friction acting on the box.
(c) Determine the acceleration of the box as it slides down the inclined plane.

  An object is placed on an inclined plane. The angle of inclib0 5m) t+j2nlhmz-; cekp; .5j xfpx. gsa-tmtne is gradually increased until the object begins to slide. The angle at which this occurs is q. W-m) j txphg0j 2nel+mz.csb p-5xmt5t.; k;f ahat is the coefficient of static friction between the object and the plane?