The force that keeps you*xmw8o ) iwajxdr(8m- from sliding on an icy sidewalk is

  It's more difficult to start moving a heavy carton from rest than it is to ke v337j 5t,yxscjqf xu 8n.3ylgep pushing it with constant velocil738gj5f, yuxyj3tsqc3n x. v ty, because

  A horizontal force accelerates a box from rest across a horizonto2 y;3 wp ,pgtvlcg/*val surface (friction is present) at a constant rate. The experiment is repeated, and all conditions remain the same with the exception that the horizontal fo32g; *pwt,cl /vg pvoyrce is doubled. What happens to the box's acceleration?

  A packing crate slides down an inclined ramp at constrix 8ju x+2op /n adyupb/y+)5ant velocity. Thus we can dxy5)+2 nr8px uijoa+ud/yp /b educe that

  A block of mass M slides down a frictionless plane inclined at an ang;)jx;x5ek1 u8ff evlg.sn: s ale q with the horizontal. The normal reg.l f:;ak s u;xv5s)ne8xf1jeaction force exerted by the plane on the block is

  A block of mass M slides down a frictionless71tgmpp:v p6vz* p 7 aq;oh1fk plane inclined at an angle q with the horifqp1;gp1 p vpt*:hv67a7kz mozontal. The normal reaction force exerted by the plane on the block is directed

  A block of mass M slides duxj1 so,jqu 17own a frictionless plane inclined at an angle q with the hor1 xj,jouu s17qizontal. The gravitational force is directed

  Two toy cars (36 kg and 7.3 kg) are released simultaneou1s1i, xpn(fi/4 xgxq msly on an inclined plane that/i(,xpgix41 fxq 1 msn makes an angle of $30^{\circ}$ with the horizontal. Make a statement which best describes their acceleration after being released.

  A person of weight 534 N stands on a scale in an eleva3vk 1wco,u8jod (wsk.5zxz5 ctor. What will the scale be reading when the elevator zx15 zcjov .(w5wudko,c83ksis accelerating downward at $8 \; m/s^2$?

  A person on a scale rides in an elevator. If the mass of the person is 60c6h.rm(;dt5kumyu t 4.0 kg and the elevator accelerates downward with an mum4u. ; tr c6(th5ydkacceleration of $4.90 \; m/s^2$, what is the reading on the scale?

  A person on a scale rid a+*2pnc5a x z(6ih y x)q)msg+0uxprtes in an elevator. If the mass of the person is 58.9 kg and the elevator accelerates upward witm* (qia0zn+ry6 gp x xsp)25 hxu+)acth an acceleration of $9.5 \; m/s^2$, what is the reading on the scale?

  In the Atwood machine shown in Fig. below, if M = 1.31 kg and m = 0.80 kg,r2/lbz m o.w:x what is the mag :.l2xmr bwo/znitude 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 =k8qgkiclwy:p u 0r 4/8 0.40 kg, what is the tension in the string? (Ignore fri:4kiqwp/8r8g0yc uk l ction and the mass of the pulley.)

  A student pulls a box of books on a smooth horizontal floor with a force of rxfm xef/;4i*65 $N$ in a direction of $37^{\circ}$ above the horizontal. If the mass of the box and the books is 52 kg, what is the acceleration of the box?

  A student pulls a box k1u:vi9m o7rzb p)bf2of books on a smooth horizontal floor with a force of 100 N in a directiz :pr7kvb )1uf9b2 mioon 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 Nj(f fm/lhhq6aa; z7r6ei1w +t is supported by two ropes as shown in Fig. below. e hi7/laja6hr6 fmwz(1t+ f;q What are the tensions in the ropes?

  In Fig. below, if the tensions in mp7 pnkv5/jr4x)sfsg8,4 yo*gc l5q sthe ropes are 22 $N$, what is the mass of the traffic light?

  Two boxes of masses m and 2m are in contact with each h dupua-+ 65ocother on a frictionless surface. (See Fig. below) What is the acceleration of the more massive box?u65 apdh-+o uc

  Two boxes of masses m and 2m are in contact with e*nh;e r9/ad1mw v4om+ t15-btxuynr k ach other on a frictionless surface. (See Fig. below) Whatxhnt;mtk b41-u*+ yr /r dw5man 9oe1v is the net force on the more massive box?

  Two boxes of masses m and 2m are conn3u qir zxz31i2o 4lxa57:csdu9ch f n6ected by a rope. (See Fig. below) If the forward force on the more massive box is F, what is the tension in the connec ca6xiun srduz3z h x4fl93ociq:27 15ting rope?

  Two boxes of masses m and 2m are connected by a rope. (See Fig. below) If tcwqkm /l*a56 k wsd.c3he forward force on the more massive box is F, what is the acceleration of the less maq3d.6k */k5sw m clacwssive box?

  Two boxes are connected by a cord running e4vb v4oh;2gd 6h:c-*b pfdtaover a pulley as shown in Fig. below Box I of mass 7.0 kg b agp * ocb;v:tv4fe4- 6h2dhdrest 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 12.0 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 bet39efmph- z0 x az(uyv,ween a 3.0-kg box and a desk are 0.40 and 0.30, respectively. What is the net force on the box when a 15 N horiz9pvu( ,-ez3 xhma0fy zontal force is applied to the box?

  The coefficients of static and kinetic frictions for plastic on wood aremc x- 5 o+nleo3xz:)8oac.gpb 0.43 and 0.3 38co+-).a mbgp ocnxo:lx5 ze0,
respectively. How much horizontal force would you need to apply to a 3.7 N plastic calculator to start it moving from rest?

  An object slides on a level surface in the +x direction. It slows and comes t 812r/mua n+iw.a9 *cz3-rl l6eyo/ qennhkbmo a stop with a constant accelerlu rqm zao9b23-a1e l6 w*inh/. c8ke+ ynm/nration of -$5.71 \; m/s^2$. What is the coefficient of kinetic friction between the object and the floor?

  A 10-kg box sitting on a horizontal surfalwo i +gf6n0 ifhzw 9j(ks-k5;ce is pulled by a 7.2 $N$ force. A 2.5 $N$ friction force retards the motion. What is the acceleration of the object?

  A horizontal force of 5.0 N accelerates a 4.0-kg mass, from rest, at a ret1 nd5k3-d/fhrlgn7+id 41teahnn1ate 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,ng q 8gpo.yyco7y-pz 83pr 9v of 10 m/s. It slides 50 m qry.8 8o 39p-gcno g7ypzyvp,on the ice before it stops. What is the coefficient of kinetic friction between the puck and the ice?

  During the investigation of a traffic accident, police find 0,mlw w,,ycae 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 conditions. Estimate the speed of the car when tc,,wa0 ely m,whe brakes were applied.

  Two boxes of masses m and 3m are stacked. (See rw6cuvqu(fd,i7d( b p8k wq5(Fig. below) The surface between the more massive box and the horizontal surface is smooth and the surface between fpd vdw7i 6kw(,(8 (urc5buqq 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 ani2kioycp/ 3.ofx )54kh5 eszhd 3m 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 ofs5ohfxyki.p)5ih23zce4ok / static friction between the boxes?

  An object is on a frictionless inclined plane. The plane is inclined20fimc7) uqcg kvv,y6 at an angle ofc6i)v20v quyf7 kc, gm $11^{\circ}$ with the horizontal. What is the object's acceleration?

  A 10-kg mass slides down a flat uy) /355r,l9 df :v vqlsqiehqhill 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 incpncb;b .u ijwpu)8 :/olined 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 inclinedb0+r tvcu .um; plane 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 inclinex4mejki06x .p d plane, at a constant velocity of 7.7 p 4m0i jxkex.6m/s.
What is the coefficient of kinetic friction, if the plane makes an angle of $44^{\circ}$ with the horizontal?

  An object with a mas 5 wls-vp.)dh77cb v,uaxw8ljs m 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 al3ot86+3l+ryamtc mm slides down a rough $37^{\circ}$ 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 a rough surface. The cable / adz.c2q(14:js gfs gfzmq.j attached to the lz(gsf4asjfqzq. m2 1j c/:.gd og makes an 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 rest on a rough inclined plane tilted at an angl 9 ;rex-glsgwt0mo.+te ofl; wot0rest-gmg9 +.x $33.5^{\circ}$ 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 igf0/ a6fe kn+qh ry l6y54)rqi. wrhw*nclined plane. The angle of incline is gradually increased until the object begins to slide. The angle at w0 k5)qhww+qr 6lrehiy/4 a*rn6gfyf.hich this occurs is q. What is the coefficient of static friction between the object and the plane?