Question

Part 3: A 20 kg box is on inclined floor as indicated in between the floor and the box is 0.5. in gure below. The static coefficient of friction 20kg 20kg 300 a) List all the forces applied on the sled. friction 20F normal force mg b) Draw free body diagram for the sled. c) What is the friction force acting on the box if a horizontal force acts on the box with a magnitude ofi) 20 N ii) 40 N iii) 60 N? Describe the motion of the box in each case.

Answer 1

mass of block (or box) = m = 20kg Coeffe cent of stafie friction butween box and inclined plane Me ting Ms = o.s marokg, 8=30° F = applied force by external agent) Ms = 0.5, g = 918 m 182 ng = granetational force by earth ts - Stafic frictional force due to contact surface f = Normal reaction fonce (by inclined plane on my o angle of inclination of inclined plane = 30° & All the forces applied on sled are given below (i) grawitational force = mg W frictional force afs Normal reaction = N. (4) Applied force =F (6) free body diagram of seed a We can wonite X = ng coso Here are assume that Esimgaino grino 20-go I ng mga if fyngaino then direction my 0-30 offs will be renessed. & C F amgann b (Fringine & morm nalue of frictional force = flim = MN tlim = Ms ng costo = 0.5x20x9 18x cos30° flim = 841878 Here surface ean Supply frectional force less then of equal to form = 84,874 mg sino = 2089188 sin30 = 98N O F= 200 de. F <ngsino (=980) the case will be shown in part bd free body diagram E me Lose Have myne ft U

box (or sledy can move downward the inclined plane if masino > (flim & F) flim & F - 84 1874 20 N = 104.87 Hingsino to block will not more in this case, because fruction is sufficient to prevent the mofron. so we can write mgsino - dst Fu fs = ng sino - f = mgrinzo -F its = 98-20-7814 i fs = 781x (frrectional force) = you ang sino (same as in case ) (flom +F)- 84187+ 40 = 124.877 mg sino so: fs = mg sine-F = 98 - Yo = 58N &. its=580 Here also box remains at rest as ind = GOM <ngnino (same as in case Üg. (from tk) = 84187 +60 = 1441878 So, fo = ng sino - f = 98-60 = 38N ifs=38N Here, in the's case also box or seed remains at rest. If we see in all aboue d a li fs I flim, that sapp's fy condition of Stafpic fruition w