Question

Problem 17.36 The desk has a weight of 89 Ib and a center of gravity at G. The coefficients of static and kinetic friction at A and B are μ·:0 5 and μ.-02, respectively. (Figure 1) Figure 1 of 1> 1 n Copyright 2019 р PartA ents of ely. Determine the initial acceleration of a desk when the man applies enough force F to overcome the static riction at A and B Express your answer to three significant figures and include the appropriate units. Enter positive value if the acceleration is to the right and negative vakue if the acceleration is t the left. Value Units Submit Part B Find the vertical reaction on each of the two legs at A Express your answer to three significant figures and include the appropriate units MVaueUnis NA" value 1 of 1 ubmit Part C Find the vertical reacion on each of the fwo legs at Express your answer to three significant figures and include the appropriate units Units N Value @ learson

Answer 1

Horizontal forcc cquilibrium of the desk Fcos30-0.5N -0.5N 0 NNFcos30 N4+N 1.732F Vertical force equilibrium of the desk to calculate the force to be applied on the desk 0.5 1.732F Fsin 3089 0 89 1.732-0.5 F= 72.237 lb Consider the desk starts to move Dynamic force equilibrium in the horizontal direction 89 72.237 cos30一0.2N,-0.2N,-ー^@g 62.559-02(N, + N,)-2.76aG 32.2 62.559-2.76 0.2 N NR 312.795-13.8la Dynamic force equilibrium to calculate the acceleration of the desk. N4 +N&-72.237sin 30-89 0 312.795-13.8lag -36.119 - 89 0 31 2.795-36·11 9-89 13.81 aG 13.589 ft/s Moment equilibrium about the leg A to calculate the reaction at B F cos30 x3-max2 89 x2 + 72 .237xcos30x3--xỉ3.589x2 32.2 N 72.638 Ib Reaction force on each leg at B 72.638 1b 36.319 lb Reaction force acting at A. N (1.732x 72.237)-72.638 N, = 52.476 lb Reaction force on each leg at A. 52.476 lb = 26.238 lb