# Answer to Question #23213 in Mechanics | Relativity for Christian

Question #23213
What is the mass of block X? Block A of mass 8.0 kg and block X are attached to a rope that passes over a pulley. A 50-N force P is applied horizontally to block A, keeping it in contact with a rough vertical face. The coefficients of static and kinetic friction between the wall and block A are &mu;s = 0.40 and &mu;k = 0.30. The pulley is light and frictionless. In the figure, the mass of block X is adjusted until block A descends at constant velocity of 4.75 cm/s when it is set into motion. What is the mass of block X? A - 6.5 kg B - 7.2 kg C - 9.5 kg D - 8.8 kg E - 8.0 kg THIS IS THE IMAGE: http://i102.photobucket.com/albums/m90/CMParts/f1q111g1_zpsf92b2525.jpg
1
2013-01-30T07:47:04-0500
The velocity is constant, thusthe net force is zero.
mA * g - T - &mu;k*P = 0
T = mX * g;

mX = (mA*g - &mu;k*P) / g = (8 kg * 9.8 m/s^2 - 0.3 * 50 N) / (9.8 m/s^2) = 6.469
kg.

It corresponds approximately to 6.5 kg.

Need a fast expert's response?

Submit order

and get a quick answer at the best price

for any assignment or question with DETAILED EXPLANATIONS!