Could anybody of you be so kind to help me a little bit with understanding what to do in this problem? Thanks in advance for your effort!(adsbygoogle = window.adsbygoogle || []).push({});

A mass m2= 10 kg slides on a frictionless table. The coefficients of static and kinetic friction between m2 and m1 = 5 kg are us= 0.6 and uk= 0.4.

http://img508.imageshack.us/img508/6309/tableproblem3tq.th.gif [Broken]

a) What is the maximum acceleration of m1?

Here I totally don't have a clue of the solution

b) What is the maximum value of m3 if m1 moves with m2 without slipping?

What I've done is the following:

fs= us * Fn = 0.6 * 9.81 * (10+5)= 88.29 N= T= m3 * g

m3= 88.29/9.81= 9 kg.

(I've calculated Fn by thinking of m1 and m2 as one system, but is that correct?)

c) If m3= 30 kg, find the acceleration of each body and the tension in the string.

For m1:

Fres= fk= uk * Fn = 0.4 * m1 * 9.81= 19.62 N

Fres= m1 * a therefore a= 19.62/5= 3.924 m/s^2

For m2:

Fres= T- fk = Fzm3 - fk= m3 * g - uk * m1 * g= 30* 9.81 - 0.4 * 5 * 9.81= 274.68 N

Fres= m2 * a therefore a= 274.68/ 10= 27.47 m/s^2

For m3:

Fres= Fz= m3 * g= 30 * 9.81= 294.3 N

Fres= m3 * a therefore a= 294.3/30= 9.81 m/s^2

Is this ok?!

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# Blocks on a table problem

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