You got to see the picture 1st.(adsbygoogle = window.adsbygoogle || []).push({});

A block of mass m1 = 2 kg rests on a table with which it has a coefficient of friction µ = 0.66. A string attached to the block passes over a pulley to a block of mass m3 = 4 kg. The pulley is a uniform disk of mass m2 = 0.5 kg and radius 15 cm. As the mass m3 falls, the string does not slip on the pulley.

--------

a) With what acceleration does the mass m3 fall?

b) What is the tension in the horizontal string, T1?

c) What is the tension in the vertical string, T3?

=======================

Okay, shouldn't be that HARD of a problem. But this is what I've done so far.

mass 1 (right is positive)

-------

Summation of forces in x direction

T1-u*m1*g=m1a

Summation of forces in y direction

N-m1g=0

N=m1g

mass 3 (up is positive)

------

Summation of forces in y direction

T3-m3*g=m3*a

My biggest question is the following equation correct:

mass 2

------

(T1-T3)R=I*alpha

simplifies to

(T1-T3)R=.5*m2*R^2*(a/R)

or

(T1-T3)=.5*m2*a => is this right for mass 2 for net torque

From here I manipulated the equations until I got a=...

This is what I have so far, but I'm not getting the acceleration value right, unless I made an algebra error.

But the equations look right so far, right?

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Two blocks and pulley systemhelp on small part

**Physics Forums | Science Articles, Homework Help, Discussion**