an 85kg concrete block rests on a flat surface with coefficient of static friction us=0.42. find the maximum force that can pull on the block with, angle of 38 degrees above the horizontal without moving the block?
please help and show work
M*g = 85 * 9.8 = 833 N. = Wt. of block.
Fn = Mg-F*sin38 = 833 - 0.616F = Normal force.
F*Cos38-u*Fn = M*a.
0.788F - 0.42(833-0.616F) = M*0 = 0, 0.788F - 349.9+0.259F = 0,
1.047F = 349.9, F = 334.3 N.