The force that keeps you f ra4 k/mo(ah,lrom sliding on an icy sidewalk is

  It's more difficult to star9gl y hx72kn4tf7y rr5t moving a heavy carton from rest than it is to keep pushing it with constant velocityfln hx452ry9g7 7rkty, because

  A horizontal force accelerates a box from rest acra nzia 3eg48v1oss a horizontal surface (friction is present) at a constant rate. The experiment is repeated,ae4z13vg8i na and all conditions remain the same with the exception that the horizontal force is doubled. What happens to the box's acceleration?

  A packing crate slides down an inclined ramp at constant )mj8.9can2d 0 k/x odz2rmtrqvelocity. Thus we can deduce thamd9 8mq0)/xo2cn j zt .rkrd2at

  A block of mass M slides down a frictim p m kg.wv;rs31 i(prza) :1q:4cqwhmonless plane inclined at an angle q with the horizontal. The normal reactio :4c)pwrg: qw1v1q msi.mmpzar(h;3 kn force exerted by the plane on the block is

  A block of mass M slides down a frictionless plane inclined at an a5: w7it3(qa2 pb -oejize h)hbngle q with the horizontal. The normal reaction force exerted by the plane(w)a: zbqieeb -oj37p25 hh it on the block is directed

  A block of mass M slides down a frictionless plane inclined at an 6o gc,wyc(19mehf 0xyangle q with the horizontal. The gravitational force is direcc fhe0m(cg1w,yo x9y6 ted

  Two toy cars (45 kg and 7.7 kg) are released simultaneow y:r5dk 4unh ;s-gda1usly on an inclined plane that makes a15 d:d g-nwsur kh4a;yn angle of $30^{\circ}$ with the horizontal. Make a statement which best describes their acceleration after being released.

  A person of weight 670 N stands on a scale in axxp2p;kp9bydnx w/ 3(,ovq 0yn elevator. What will the scale be reading when0 owv ypkx;,npx2b(yq dp3x/9 the elevator is accelerating downward at $2 \; m/s^2$?

  A person on a scale rides in an elevator. If the m4,vqclgk7n9*ldc; v g tqqy3r;wn :5y ass of the person is 60.0 kg and the elec*rvvtql;dcy g3l7 ,y9 g4n;w5qn:qkvator accelerates downward with an acceleration of $4.90 \; m/s^2$, what is the reading on the scale?

  A person on a scale idivuf4fd n ;( 6f2lm8rides in an elevator. If the mass of the person is 46.1 kg and the elevator accelerates f 8m(uin6l42v; dfdfi upward with an acceleration of $19.3 \; m/s^2$, what is the reading on the scale?

  In the Atwood machine shown in Fig. below, if M =wxag: .lhr 36 -hcbp.hyyd.n. 1.89 kg and m = 0.72 kg, what is th:3. hg..6bcpaxy hr dlhn-w.ye magnitude of the acceleration of the system? (Ignore friction and the mass of the pulley.)

  In the Atwood machine shown in Fig. below, i9a:z 43s1a tldkgiqj8m q6hr -f M = 0.60 kg and m = 0.40 kg, what is the tensi9m qkrdas1qzi g:l6t4-38jhaon in the string? (Ignore friction and the mass of the pulley.)

  A student pulls a box of books on a smooth horizontal floor p*+4+-vj htbjh ;x ewit(2lhmqg()ffwith a force of 45 $N$ in a direction of $37^{\circ}$ above the horizontal. If the mass of the box and the books is 33 kg, what is the acceleration of the box?

  A student pulls a box of books on al1m*f +( riya-ra*rm e smooth horizontal floor with a force of 100 N in a dire ma-yfr+li1rm(** eraction 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 shownuwj7nh9(*jqe in Fig. below. What are thejn97 u *jhq(we tensions in the ropes?

  In Fig. below, if the.ptmp kq ko) t5ri*9:u tensions in the ropes are 57 $N$, what is the mass of the traffic light?

  Two boxes of masses m and 2m are in contacrbbh;a 0lgh0 9t with each other on a frictionless surface. (See Fig. below) What is t0g alb;h90hr bhe acceleration of the more massive box?

  Two boxes of masses m and 2m are in contact with each other on a frri2qmu7ww cqrbpmf z 005:05tictionless surface. (See Fig. bw205zbm mt 50:i0 puqwrf7cqr elow) What is the net force on the more massive box?

  Two boxes of masses m and 2m are connected by axg38ke c2veb ) rope. (See Fig. below) If the forward force on the more massive box is F, what is ek8e xc3b2g)vthe tension in the connecting rope?

  Two boxes of masses m and 2m are connected by a rope. (See Fig. below) I bot 8upyadtvcq, r*f,+- 0kv)f the forward force on the more mass0p-vt,c oufqk*br8dayt , +)vive box is F, what is the acceleration of the less massive box?

  Two boxes are connectytequ- tp9tx,m xaju xh ; /sku36p6;2ed by a cord running over a pulley as shown in Fig. below Box I of mass 6.9 kg rest on the top of the table;squ tx ;u,kjuxt/-h ;xpam63y 2pt6 9e 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 frictiony* y*kbm4id n2s between a 3.0-kg box and a desk are 0.40 and 0.30, respectively. Whiyny4*b2km* dat 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 zwlh3 k9( cspp2iv k87wood are 0.42 andk7wp hc 8k2 zi(vslp39 0.33,
respectively. How much horizontal force would you need to apply to a 9.5 N plastic calculator to start it moving from rest?

  An object slides on a level wbl5o7r(wos82u s1jusurface in the +x direction. It slows and comes to a stop with a constant acceleration2j8 ls wsrwo7( 1uob5u of -$4.88 \; m/s^2$. What is the coefficient of kinetic friction between the object and the floor?

  A 10-kg box sitting on a horizontal surface is t),b*elslpzgitl*w;o 14 0x qpulled by a 7.9 $N$ force. A 1.3 $N$ friction force retards the motion. What is the acceleration of the object?

  A horizontal force of 5.0 N acchh1 x;pi(f 0pf/(8yd6ii tera elerates 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 i8ij +-) haoypss given an initial speed of 10 m/s. It slides 50 m on the ice bey8pa h+j -os)ifore it stops. What is the coefficient of kinetic friction between the puck and the ice?

  During the investigation of a traffic accident, police find skid marks 90(r)el g8ls4bqwk 7t5/cn 2xrw lkio 97.0 m long. They determine the coefficient of friction between the car's tires anibqg245 lwtxl789( ewn/sk7ro) lkrcd 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. b( ) 7gjxp,zramelow) The surface between the more massive box and the horizontal surface is smooth and the surface between the amjg r)z,(px 7boxes 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. (See3/3niwo+ gs( v qi7smm*pj9r z 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 do9sw z* 33r vnsp mqim(gijo+/7es not slide on the more massive box, what is the coefficient of static friction between the boxes?

  An object is on a frictionless inclined p.uky k(/v 3jkplane. The plane is inclined at an angle of(ju3yp/k.k kv $14^{\circ}$ with the horizontal. What is the object's acceleration?

  A 10-kg mass slides down a flat hill that makes an angle of * wiocja2 tsakg389d2$10^{\circ}$ with the horizontal. If friction is negligible, what is the resultant force on the sled?

  A mass is placed on a smoo/ j95kg skoql;th 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 +ro r5 b3/ergnwrv c60inclined 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 afnv(*m kn)rppqd4 j4jd 051/x m)ffwkn inclined plane, at a constant velocity of )*jfdnp) 4mdfmxp1w /jv n0r(kq45k f5.3 m/s.
What is the coefficient of kinetic friction, if the plane makes an angle of $22^{\circ}$ with the horizontal?

  An object with a mass m slides down a rough ;n9kc q 6(qwmv$37^{\circ}$ 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 rog761h7z)ulsvfej x ;eugh $37^{\circ}$ inclined plane where the coefficient of kinetic friction is 0.17. 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 53xrepj*ev*,(pw v4xu00 N along a rough surface. The cable attached to * xu eppew4 v,xr3*jv(the log 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 8(cf bi)h;6uy0 rsbpm8rw bm6inclined plane tilted at an angle ou0r mbc(h;)b6prm8w if s8yb6f $33.5^{\circ}$ 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 in.6 4 iemupblx7vb2x k33uo td(g. -kafclined plane. The angle of incline is gradually increased until the object begins to slide. The angle at which thi eu.bv a7p 3i.2o kxlf-gd(xk36tb4mus occurs is q. What is the coefficient of static friction between the object and the plane?