The force that keeps you from sliding on an icy sideb,iotvns:njknk e9n5c evn , g/-.8z6 b/m3nlwalk is

  It's more difficult to start moving a mb0tu86po.p m.hjw. aheavy carton from rest than it is to keep pushp8p0ab t.who6uj .mm.ing it with constant velocity, because

  A horizontal force accelerates a box from rest across a horizontal surft6 /d rkg)nsru5l u8c6ace (friction is present) at a constant rate. The experiment is repeated, and all condi n/du86tcu lrksr6g5) tions remain the same with the exception that the horizontal force is doubled. What happens to the box's acceleration?

  A packing crate slides down ank3x b1xko smces6k3w(d ) 9xz3 inclined ramp at constant velocity. Thus we can dbs9 1(xz kmx 3ks3e wo)6ck3xdeduce that

  A block of mass M slides down a frictionless plane inclined at an ang 0 dqpaas,n:r ;gh8vv+le q with the horizontal. The normal reactiogad8rn v:,pasv h+ q0;n force exerted by the plane on the block is

  A block of mass M slides down a frictionless planmufdfu 8:f79a e inclined at an angle q with the horizontal. The normal reaction for ma8:ufd 9f7fuce exerted by the plane on the block is directed

  A block of mass M slide xx22jheierok1+9+-vr lx-rus down a frictionless plane inclined at an angle q with the horizontal. The gravitationale+k+ vhu r22ix9e 1- rr-xljox force is directed

  Two toy cars (39 kg and 4.5 kg) are released simultaneously on an inclm2gd.s 04 2 uuffo,wdkined plane that makes an angle o ms f,u0wo4.22kufddgf $30^{\circ}$ with the horizontal. Make a statement which best describes their acceleration after being released.

  A person of weight 710 N stands on a scr cv1yo6v73fk4nn wc6tp92h gale in an elevator. What will the scale bhvcvgcnyt 24n 73rk 6w6p91ofe reading when the elevator is accelerating downward at $2 \; m/s^2$?

  A person on a scale rides in an elevj:qa+c, .ubh7pn8:cxtocbxg ti) : 9iator. If the mass of the person is 60.0 kg and the elevator accelerates downward witc:n x: :abpui7o8tcjb 9q.cxi ,) +htgh an acceleration of $4.90 \; m/s^2$, what is the reading on the scale?

  A person on a scale rides in an elevator. If th.7k/;gdfvmm py3 shq 6e mass of the person is 56.4 kg and the elevator accelerates upmygpq;3v.6kd 7/h fsmward with an acceleration of $10.6 \; m/s^2$, what is the reading on the scale?

  In the Atwood machine shown in Fig-eqsll 6-sb5w6oa1k g. below, if M = 1.95 kg and m = 0.76 kg, what is the magnitude of the acceleration of the system? (Ignore f6gowqlkb 1a5s6l--esriction and the mass of the pulley.)

  In the Atwood machine shown in Fig. below, if M = 0.60 kg and m = 0.4d2 lsgd qfjs rmf;y72 i3u0h180 kg, what is the tension in the string? (Ignsqg 1i2jm;hur 8f f3dd s270lyore friction and the mass of the pulley.)

  A student pulls a box of books on a smooth horizontal floor with a force of 6tey- o3wy87vl3uu.l bslt o+93 $N$ in a direction of $37^{\circ}$ above the horizontal. If the mass of the box and the books is 36 kg, what is the acceleration of the box?

  A student pulls a box of+xf)x d . pylz0-qf1dx books on a smooth horizontal floor with a force of 100 N in alxq0fdz1+) xx. df -py direction of $37.0^{\circ}$ above the horizontal. If the mass of the box and the books is 40.0 kg, what is the normal force on the box?

  A traffic light of weight 100 N is supported by two ropes as showe* 9tz .8qpj4bq:rncb n in Fig. below. What arrn jzp8* qbc .t9b:4eqe the tensions in the ropes?

  In Fig. below, if the tensions in the ropes wir/3*dv 0s sf 6s:oehare 36 $N$, what is the mass of the traffic light?

  Two boxes of masses m and 2m are in contact with each otheo ezz1.j0ey*;pi ff* 1or-r*ategrc 1r on a frictionless surface. (See Fig. below) What is the acceleration of eo*zrgz1 fe1 p1faycrr-0 * toi*j.e ;the more massive box?

  Two boxes of masses m and 2m are in contact with each other8 mw 6qt gf00xo.bdu,p on a frictionless surface. (See Fig. below) What is the net force on the more massive boxdpqmo6 0,.b utg8xwf0 ?

  Two boxes of masses m and 2m are connected by a rope. (See Fige zu,vzgwk ,n6m+wz b:fn4/e4. below) If the forward fon /v4 zw, m,eb+f:6ugzzew4n krce on the more massive box is F, what is the tension in the connecting rope?

  Two boxes of masses m and 2m are connected by a rolm- d8;ig6n.v qorbz6pe. (See Fig. below) If the forward force on the more massive box is F, what is the acceleration of the less massi6zv;ml i o6qgdb r-8.nve box?

  Two boxes are connected by a cord running overzy(dn*e7+ft(ue lmj5 a pulley as shown in Fig. below Box I of mass 5.2 kg rest on the top of the table; the coefficient of kinetic friction between box I and the table is 0.10. Box I7em z5(+jy*ndutlf e(I has a mass of 14.3 kg.
(a) Calculate the acceleration of the system  (数值)  $m/s^2$
(b) Calculate the tension in the cord  (数值)  $N$

  The coefficient of static and kinetic frictions between a idord)m xvngh/b-e1f:0 n9 m+3.0-kg box and a desk are 0.40 and 0.30, respectively. What is the 9idrn1mno+:e v b 0m-x)dghf/net force on the box when a 15 N horizontal force is applied to the box?

  The coefficients of static and kinetic frictions for plastic on wood are 0.48 azqc*t -bmqa.*nd 0.32qc bmt.a **-qz,
respectively. How much horizontal force would you need to apply to a 8.5 N plastic calculator to start it moving from rest?

  An object slides on a level surfac3dwx qf5 .uvx7e in the +x direction. It slows and comes to a stop with a constant acceleration of5wqxvd x f3.u7 -$4.32 \; m/s^2$. What is the coefficient of kinetic friction between the object and the floor?

  A 10-kg box sitting on a horizonta7x n,so, kxt8-j/s)tr je*k vel surface is pulled by a 6.4 $N$ force. A 2.8 $N$ friction force retards the motion. What is the acceleration of the object?

  A horizontal force of 5.0 N acceler)8 gcq*j4hhw hates a 4.0-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 a5z es0dyh 6 d(+ (i,ph- burdatjnd.i3n initial speed of 10 m/s. It slides 50 m on the ice before it stops. What is the coefficient of kinetic fd+hye-( sui0 d.35drj,d a6 ptb n(hizriction between the puck and the ice?

  During the investigation of a tx w tgh3 :tdk9;e:kga9ph3 ae4raffic accident, police find skid marks 90.0 m long. They determi kxhek;9 tagha3pg:dew 49t:3ne the coefficient of friction between the 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. belo-n-0cm 0ievtzp 1dq 4nw) The surface between the more massive box and the horizontal surface is smooth andv z ecdqp0 n0t-mn4i1- the surface between the boxes is rough. If the less massive box does not slide on the more massive box, what is the static friction force on the less massive box?

  Two boxes of masses m and 3mmw 1 j8hfzh-,q are stacked. (See Fig. below) 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 is the coefficient of static friction between the 8z1m j-,hq hfwboxes?

  An object is on a fricuxjd9h b)cw56v4:n8 /b x ktwstionless inclined plane. The plane is inclined at an anglebx8 :tcd)n su vx6w59k jhw4/b of $56^{\circ}$ with the horizontal. What is the object's acceleration?

  A 10-kg mass slides down a b4 tzezyv// q1flat hill that makes an angle of $10^{\circ}$ with the horizontal. If friction is negligible, what is the resultant force on the sled?

  A mass is placed on a smooth inclined planecpn26m;ttb,f 9 wmnt9 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 tilted at an angle of 8zdj5pm:g hn(- jpky muh .+0d6fkqte;om-f8$35^{\circ}$ 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 inclipr z6.k mo4y9ened plane, at a constant velocity of 7.1 4. 6ypomezkr9m/s.
What is the coefficient of kinetic friction, if the plane makes an angle of $35^{\circ}$ with the horizontal?

  An object with a mass m slides down a rooe -w4ll2fz( zugh $37^{\circ}$ 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 rough 4 r,9yybs.:pqlkg s2y$37^{\circ}$ inclined plane where the coefficient of kinetic friction is 0.13. If the plane is 10 m long and the mass starts from rest, what will be its speed (m/s) at the bottom of the plane?

  A bulldozer drags a log weighing 500 N along r. -fcqtu-k3ea rough surface. The cable attached to the log makes an angle of-fk.-cqure t3 $30.0^{\circ}$ 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 rest on a rough inclined pp03yttgngc.xoeg ) * 8lane tilted at an angle o ggetg.8c)tn py03*xo f $33.5^{\circ}$ 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 ohhg l 37d.78 iqmt8quangle of incline is gradually increased until the object begins to slide. The angle at which thdhgmlqt778ihqo.3 8 u is occurs is q. What is the coefficient of static friction between the object and the plane?