Hey people,

im really stuck on this and wondered if you could help please.

Q: A heavy crate of mass m is pulled along a rough horizontal surface at a constant speed by a rope. The coefficient of friction between the crate and surface is u (substituted for mew as i dont know how to insert that)

http://www.mathhelpforum.com/math-he...20Pictures%5Ct
A) Show that T = umg/(cos(theta)+usin(theta).

B) By finding dT/d(theta) and letting dT/d(theta) = 0, show that for a minimum value of T , tan(theta) = u. ( you may assume that, for a maximum value of T, (theta) = 0).

any help would be really greatful guys as im really stuck.

thanks.