Posted by Bob on Sunday, May 6, 2012 at 8:13pm.
Two block are connected by a rope that runs over a pulley. The block on the tables has mass 4kg, the hanging block has mass 2kg, and the pulley has mass 0.5kg and radius 0.25m. Assume that the table is frictionless. If the block are released from the rest, determine their speeds after the hanging block has dropped 0.75m.

Physics 121  Elena, Monday, May 7, 2012 at 8:39am
m1 =4 kg, m2 = 2 kg, m = 0.5 kg, R = 0.25 m, h= 0.75 m.
Projections on the horizontal and vertical axis:
m1•a = T1
m2•a =m2•gT2,
I•ε =M.
If the pulley is the disk (cylinder) I =m•R²/2 ,
M = torque = (T1T2) •R,
ε = a/R,
I•ε =M => m•R²•a/2•R =(T1T2) •R =>
m•a/2 = (T1T2).
m1•a + m2•a = T1 + m2•g T2 = m2•g + (T1T2) = m2•g +m•a/2,
a = m2•a/[m1+m2m(m/2)] = 2•9.8/(4+2+0.125)=3.336 m/s^2,
a = v^2/2•h ,
v=sqrt(2•a•h) = sqrt(2•3.336•0.75) = 2.2 m/s^2
Answer This Question
Related Questions
 Physics 121  Two block are connected by a rope that runs over a pulley. The ...
 phy  (Q1)A 40N force applied at an angle of 37c above the horizontal pulls a ...
 Physics  calculate the acceleration of this system, assuming that there are no ...
 Physics Dynamics  A 4kg block is connected by means of a massless rope to a 2...
 physics  Two blocks are connected by massless string that is wrapped around a ...
 Physics Help Needed  Two blocks are connected by massless string that is ...
 physics  A block (mass = 2.9 kg) is hanging from a massless cord that is ...
 Physics  A block of mass m1 is on top of a block of mass m2. Block 2 is ...
 Physic  A block (mass 2.4 kg) is hanging from a massless cord that is wrapped ...
 physics  Two blocks are connected with a light string that is hung over a ...
More Related Questions