A box of mass 1kg is placed on a table and is connected to a hanging mass m by a string strung over a pulley. If the coefficient of kinetic friction between the box and the table is .3 and the box slides at a constant speed of .5m/s what is the weight of the hanging mass?

Question

Would the acceleration of the 1kg box be zero? Since direction is constant and the speed is also constant. Thus to find the weight of the hanging mass:

F_box=Fg of hanging mass
ma=mg
(1kg)(0m/s^2)=m_hanging(9.8m/s^2)
m= 0kg but this is not possible what did I do wrong?

Answer 1

Weight will equal friction, mu*mg

If it is at constant velocity, acceleraeration is zero.

mu*mg= .3*g is the hanging mass.