# the pulley is massles and frictionless

0 votes
1,934 views

-----------------------------------------------------------------------------------

asked Sep 26, 2014
reshown Sep 26, 2014

## 1 Answer

0 votes
Question Body: The pulley is massless and frictionless attached to the ceiling. A massless inextensible string is attached to the masses Ma and Mb, where Ma > Mb . The tensions Ty, Tz, Tx, and the gravitational constant g are magnitudes.

First part: Ma>Mb so the system is going to accelerate counter-clock wise, Ma going down and Mb going up.

Therefore, $T_y<M_ag$ and $T_x>M_bg$.

With massless strings and pulley, the tension inside a single string is constant. $Tx=T_y$.

Do a free body diagram of the top pulley. $T_z=T_x+T_y$. Since the two blocks accelerate downward, $T_x+T_y<M_ag+M_bg$.

The magnitude of acceleration along a single string is the same. So the two blocks will have the same acceleration in magnitude.
answered Sep 26, 2014 by (21,750 points)