The force that keeps you from sliding onog)eoi 4.ax-oe h5h ,y an icy sidewalk is

  It's more difficult to sta* umcb,na tq t7we 75rfiq)pp7c6c35irt moving a heavy carton from rest than it is to keep pushing it with cp n7r6qi*5 t bca7w, f)eqt73mupic5c onstant velocity, because

  A horizontal force accelerates a box from rept7y),t4 m thhst across a horizontal surface (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.h 74tytpm) ,th What happens to the box's acceleration?

  A packing crate slides down an inclined ramp at constant velocxovuwjo-+lup)( *643o:g pomd h;uz c)bks1x ity. Thus we can deduce thajku*vlzoox1m3)xopd+p (64ug scbh-)o;:w u t

  A block of mass M slides down a frictionless plane iqvg. x3 q1.rvunclined at an angle q with the horizontal. The normavrxq3. .v qug1l reaction force exerted by the plane on the block is

  A block of mass M slides down a frie lt6 pzd.h9c7ctionless plane inclined at an angle q with the horizontal. The normal reaction fo.tzdc 7lhep69rce exerted by the plane on the block is directed

  A block of mass M slides down a frictionless plane inclined at an36xserrh/ - u qnd/k7k angle q with the horizontal/6 du- /kshe73rqxnk r. The gravitational force is directed

  Two toy cars (29 kg and 2.8 kg) are released simultaneously on an in5 (wq(6kfsdo cgcn( 6bclined plane that makes an angle ofonw g5d( ccf6((6b qks $30^{\circ}$ with the horizontal. Make a statement which best describes their acceleration after being released.

  A person of weight 506 N stands on a scale in an elevator. What wt.t 53x lxj*haill the scale be reading when the elevator is accelerating downwa xx.lh5a*j3 ttrd at $8 \; m/s^2$?

  A person on a scale rides in an elevator. If the mass of the person is 60.0 kg 9 ,hdl5 yam qttya(e0 o/k)yr*and the eleva(eymlk r/0y 5)t*dyaqh ta 9,otor accelerates downward with 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 the mass of the pe (fzs+5*hkvz xrson is 44.3 kg and the elevator accelerates upward with an accelerashfkz+* (5zv xtion of $4.5 \; m/s^2$, what is the reading on the scale?

  In the Atwood machine shown in Fig. below, y*zpkjo1xqu:x ( 6zi: if M = 1.94 kg and m = 0.59 kg, what is :1j*y x :u6xzzpk(qiothe magnitude of the acceleration of the system? (Ignore friction and the mass of the pulley.)

  In the Atwood machine shown in Fig. below, if M = 0.60 kg and m = 0.40 kg,bq y3zz(3i5dpo/l3is4 s 1f jc what is the tension in the string? (Ignore friction and the mass of to3ij cz51qi/l dsy bz34 (fps3he pulley.)

  A student pulls a box of books on a sm1bpnxutqn/ k33p :bo*ooth horizontal floor with a force of 80 $N$ in a direction of $37^{\circ}$ above the horizontal. If the mass of the box and the books is 53 kg, what is the acceleration of the box?

  A student pulls a box of books on a smooth horizontal flooa h 6mwe9ud9b7r with a force of 100 N 79ha9 dmeb 6wuin a 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 twoig vxe5 1aq(b/ gj hae(6*mg4i ropes as shown in Fig. below. /5ab qhm4g e(ig 16xi*ae vj(g What are the tensions in the ropes?

  In Fig. below, if the tensions in the ropes a6 ek9kjot1yu e0, b-td 0fte/gre 73 $N$, what is the mass of the traffic light?

  Two boxes of masses m and 2m are in contact wiy,)xax*kws dm ana)pecx+5h-vt 0;+c th each other on a frictionless surface. (See Fig. below) Wa svc;)nd x+5-xya,w tmk p* hx)c+0eahat is the acceleration of the more massive box?

  Two boxes of masses m and 2m are in c7rw5i0w 7prlb9 ltj*aontact with each other on a frictionless surface. (See Fig. below) What is the net forc7rpi wa79 jwb5l 0rl*te on the more massive box?

  Two boxes of masses m and 2m are connected by a rope. (See wbm* -wf3iprq() tjq5to.b ,mFig. below) If the forward force on the more massive bomf3q * o m-,b5ibqt w)jrp(tw.x is F, what is the tension in the connecting rope?

  Two boxes of masses m and 2m are connected by a rope. (See Fig. below) If 4i;3m(c )s p0 e04wrdc/9rjkslu lk kithe forward force on the more massive box is F, what is 3rllkr;m4p (/sk d 0ciij)e49kuwc s0the acceleration of the less massive box?

  Two boxes are connected by a cord running over a pulley as shown in Figt ekn:e2+ vt4o. below Box I of mass 9.1 kg rest on the top of the vtte :42+enoktable; the coefficient of kinetic friction between box I and the table is 0.10. Box II has a mass of 12.3 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 3.0-kg bowdylhvah1 2 d8d c265agwg4yho)/xz 1x and a desk gl2gdz)1/x 8h1 dway5 wdhh42v cya6oare 0.40 and 0.30, respectively. What is the net force on the box when a 15 N horizontal force is applied to the box?

  The coefficients of static and kinetic frictions o:j mrfo 7g c(.m5q4j d4fin2tfor plastic on wood are 0.40 anonrg4j4 mjq7(df 2tc 5:.miofd 0.33,
respectively. How much horizontal force would you need to apply to a 3.3 N plastic calculator to start it moving from rest?

  An object slides on a level surface in the +x direwklx-3(ujx1 ue mcvq1cq,s6-ction. It slows and comes to a stopqkc ql1-1(j x6s w u3,uecxv-m with a constant acceleration of -$3.20 \; m/s^2$. What is the coefficient of kinetic friction between the object and the floor?

  A 10-kg box sitting on a horix 8j ,7u(h8hgfw2 p(2ogaqrsy zontal surface is pulled by a 8.5 $N$ force. A 1.2 $N$ friction force retards the motion. What is the acceleration of the object?

  A horizontal force of 5.0 N a5r 9zri0-qgck ccelerates 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 an initial speed of 10 m/s. It :,7nzp0 (gc 6nclvll kslides 50 m on the ice before it stops. What is l6l0 gcz:n nlv(k7c, pthe coefficient of kinetic friction between the puck and the ice?

  During the investigation of a traffic accident, a byb9io+ m b +hm;kmiib*,b91police find skid marks 90.0 m long. They determine the coefficient of friction between the car's tires and the roadway to be 0.500 for the prevailing cb,ib1a+m9*bmoi hy b+9bk; imonditions. Estimate the speed of the car when the brakes were applied.

  Two boxes of masses m pppu,m i (46urp2 ojv2and 3m are stacked. (See Fig. below) The surface between the more massive box and uppj,2(pm2 o4 pvuri6the 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 static friction force on the less massive box?

  Two boxes of masses m and 3m are stacked. (See Fig. below) nwt-:ni1lx ct23lb e7 The surface between the more massive box and the horizontal surface is smootc2lw1ext- tnb7i : l3nh 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 boxes?

  An object is on a frictionless inclined plane. The plane is inc)(a:7byzlfu;,pje d nlined at an angle djy l(:e,fzpuab7 );nof $28^{\circ}$ with the horizontal. What is the object's acceleration?

  A 10-kg mass slides down a flat hill that makes kh3d / i7s v j.vzqwa*pwu(rpunt .fd37).ia9an 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 smoh;q7;wcxg .0kig 5x.v mu)fu1jrod- goth inclined 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 planep ld70z,wblm 8 tilted 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 a conn: buswx17 6aostant velocity of 2.0 m/sws o6 uxn17ba:.
What is the coefficient of kinetic friction, if the plane makes an angle of $21^{\circ}$ with the horizontal?

  An object with a mass 9aq u sh k:;-ojag.9qxm slides 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 downswmt *ctd,h rts(j +69 a rough $37^{\circ}$ inclined plane where the coefficient of kinetic friction is 0.12. 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 a rough surfy1,yx68z jss2f fc4 pcace. The cable attached to the log makes an angle offfc 2 s4cjp z8y6,sxy1 $30.0^{\circ}$ 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 plane,cfqesb(z: - j tilted at an angle oc q(fb-:e js,zf $33.5^{\circ}$ 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 incli j,7i nj ctawjm 1;0(krwbo47jcr8l4ine is gradually increased until the object begins to slide. The angle at which this occurs is q. What is the coefficient of static friction between the object andt iwo8jarbr 0cjckwm,4; 177 jjinl4( the plane?