The force that keeps you from sliding on an icy s4 dx5mrr9klo5 idewalk is

  It's more difficult to start moving a heavy carton frsa*24i 7 *mt)mpq se1yee gw5tom rest than it is to keep pushing it with constant velocity, becaumes*typ 4ge q asewt 7)i*2m15se

  A horizontal force accelerates a box from re5hfnr)-vva c t:22,n dh4n qhest 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. What happens to ta nh)vtqh en2-,r:h 42fv d5cnhe box's acceleration?

  A packing crate slides down an inclinedd:8e04bc 0jg4 uuwl zn ramp at constant velocity. Thus we can d :48wejbdu0uz40lcgn educe that

  A block of mass M slides down a frictionless plane incw kdey26 c8* eeyxh9c-ix/)xvf5;g kclined at an angle q with the horizontal. The normal reaction force exerted by the plane on the bloe/9 hg;c- wc kxyi fxed*c vx8)26e5kyck is

  A block of mass M slide153b( +)gbe:fu vlvnheng5wvs down a frictionless plane inclined at an angle q with the horiz5fu3g(:w+5h eb v1lbgenvv) nontal. The normal reaction force exerted by the plane on the block is directed

  A block of mass M slides down a frictionless plane inclined at an anglewi+s)ejl o 9t/ oc0r50jlx 2iy q with the horizontal. The 0s0ljc2iot9)+or 5l /x iejywgravitational force is directed

  Two toy cars (26 kg and 7nml ,cl o l((s 6k:,8oalrwge8.0 kg) are released simultaneously on an inclined plane that makes an angle : (l8wg nkslo6cl lr e(mo7a,,of $30^{\circ}$ with the horizontal. Make a statement which best describes their acceleration after being released.

  A person of weight 714 N stands on a scale in ak6uiii9ho reo ro1c ( 7s)qa6-n elevator. What will the scale be reading when the elevator is accelerating dsa o661orrh- 9iei)( 7cokuq iownward at $3 \; m/s^2$?

  A person on a scale rides in an elevator. If the mass of the person is 6hgk78f6w -tca* gof37n0mls g0.0 kg and the elevator accelerates downward with an accekh* c7ta 6nwoml7f f 3g-g0s8gleration 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 peas aydcd8c v;s/k/ j67rson is 59.0 kg and the elevator accelerates upward with an accelerationvk8yajacs //;ddc7 s 6 of $2.0 \; m/s^2$, what is the reading on the scale?

  In the Atwood machine shown in Fig. below, 8 ym5:ocuptk-np s3zlntr21. if M = 1.94 kg and m = 0.86 kg, what is opk: yl-nu25 cp13t rst8mzn.the magnitude of the acceleration of the system? (Ignore friction and the mass of the pulley.)

  In the Atwood machine s 7km w8wcc0azmvon8dh) 2;2ql hown in Fig. below, if M = 0.60 kg and m = 0.40 kg, what is the tension in the string? (Ignore friction and the mass of the pulley.7h2mnkaw0 82m; vc)cozl8d qw )

  A student pulls a box of books on a smooth horizontal floor wi) cyi* sro vab0ww)2+oth a force of 71 $N$ in a direction of $37^{\circ}$ above the horizontal. If the mass of the box and the books is 40 kg, what is the acceleration of the box?

  A student pulls a box of books on a smooth horizontal floor with a fo9bh3 ok3jwp0 dz -amw3rce of 100 N in a directiodwmpk3hjz3o -b9w a03n 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 shn72a p6+ttgut/i a4 d*l3 ovssown in Fig. below. What are the tensions il/n6itd 3a*ag4t vt2u s7po+ sn the ropes?

  In Fig. below, if the tensions in the ropes are 64g3jxc+x9 +ckjvn 48bb5o:qhc $N$, what is the mass of the traffic light?

  Two boxes of masses m and 2m ,*oe5p x13 xjuq7nrj lz5lzq1 are in contact with each other on a frictionless surface. (See Fig. below) *q7 qxj nxlolzpu5rz35 e,1j1What is the acceleration of the more massive box?

  Two boxes of masses m and 2m are in contact with each other on a frictionlessiv23:2 iutt/ 3ts3luxcalyr.ub ;7vv surface. ( bx 3r7v.l vva:t;/u i uty2tuc23i3lsSee Fig. below) What is the net force on the more massive box?

  Two boxes of masses m and 2m ar dz4 0/ sg7siblw15zd c/*chste connected by a rope. (See Fig. below) If the forward force on the more massive box is F, what is the tension in the c1sb*cs/ 5dwdcg0ls7 4 tz/ihzonnecting rope?

  Two boxes of masses m and 2m are connected by a rope. (See Fig. belaj(+ -cb1yf mmey*nxn v6gh()ow) If the forward force on the more massive box is F, what is the fnjx)n1-gy (m 6h*+beav ymc(acceleration of the less massive box?

  Two boxes are connected by a cord ru,b.7ma) kkhe:uq6 8 xsh2 gxstnning over a pulley as shown in Fig. below Box I of mass 6.8 kg rest on the top of the table; the coefficient of kinetic fri27q ha t:sxmx 8ksh)bku, 6e.gction between box I and the table is 0.10. Box II has a mass of 14.8 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 k9qg9ldal60 mt)cmr4f / bea 0sinetic frictions between a 3.0-kg box and a desk are 0.40 and 0.30, respectively. Whatmdm0tb609a q rlgec/s 49) fal 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 for plastic on wood are on l5i,7mp 7sfx pu8b/0.47 and 0p8/m ,7 sxlibpnfou 57.30,
respectively. How much horizontal force would you need to apply to a 13.2 N plastic calculator to start it moving from rest?

  An object slides on a level surface in the +x direction. It slovxmne)-r6 ;fg ws and comes to a stop with a constant acce)m ;6-fergxn vleration of -$1.89 \; m/s^2$. What is the coefficient of kinetic friction between the object and the floor?

  A 10-kg box sitting on a horizontal surface i i5 +d;njjbc o(ysqw+zk3gz,2 s pulled by a 8.0 $N$ force. A 1.6 $N$ friction force retards the motion. What is the acceleration of the object?

  A horizontal force of 5.0 N accelerates a 4.0-kg mt,-zk8 u dk9gmass, 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 innxxq.t:6r 2w rt9s /fnitial speed of 10 m/s. It slides 50 m on the ice before it stops. What is the coefficient of kinetic friction between the p w x:r.96rn/qfx stt2nuck and the ice?

  During the investigation of a traffic accident, polncrx qf/-gd6(g9f5h bwf 4xf*ice 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 conditions. Estimate the speed of the car when the x/6(f5 rw 9cg-4nhxf fgbd*qfbrakes were applied.

  Two boxes of masses m :/uvp 3rxj mlv.*hc7l and 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 uhcxvr.:v/j l7lp 3m* 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) The surface between /4id7ns1mjccz 3 rx0g-rodk* the more massive box /c7*dxs3zgc4o1m kd0nr r -ijand 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 boxes?

  An object is on a frictions5v5 s9wgvo9gljfa9;less inclined plane. The plane is inclined at an angle og;vgo95s a9 9ls fwjv5f $26^{\circ}$ with the horizontal. What is the object's acceleration?

  A 10-kg mass slides down a flat hill t*h;i t 9bu59obd b-fm-wr/sxlhat 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 plane with an angle o6p4wy p2/jw 8ojy p1uyf $37^{\circ}$ 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 dmt8ys4 9:zsi inclined 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 dzx(mq4pfgxz: +(q5x virectly down an inclined plane, at a constant velocity of 3.4 m/sx(mx+ (f v:z5 gpz4qxq.
What is the coefficient of kinetic friction, if the plane makes an angle of $10^{\circ}$ with the horizontal?

  An object with a mass m slides vszrjf*pwb,e48 h c8+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 slide7n)h v* sln0e0cn-jpk s down a rough $37^{\circ}$ 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 (m/s) at the bottom of the plane?

  A bulldozer drags a log weighing 500n oc:k g)ev8c, N along a rough surface. The cable attached to the log makes an angl vn)o8ck:ce,ge 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 inclhqtj:i ng*;l + kskt:9d,cy.;wgybt8 ined plane tilted at an angle of+i:qyt.d9c ;:*k8 lgst y;,nhkg tj wb $33.5^{\circ}$ 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 inclin(xhqq)fc255dibz uf* ed plane. The angle of incline is gradually increased until the object begins to slide. The angle at which this ocfciq q x25 ubz5*(hdf)curs is q. What is the coefficient of static friction between the object and the plane?