Four masses are suspended on weithless strings as shown below The tension T1 in the top string is
2 points
T1 = m1+m2+m3+m4
T1 =( m1+m2+m3+m4)g
T1 = m1*g
none of the above
Other:

The tension in the second from top string is *
2 points
T2 =( m1+m2+m3+m4)g
T2 =( m2+m3+m4)g
T2 =( m1+m2)g
T1 =( m1)g

Air is contained in a variable-load piston-cylinder device equipped with a paddle wheel. initially, air is at 400 kpa and 17°c. the paddle wheel is now turned by an external electric motor until 75 kj/kg of work has been transferred to air. during this process, heat is transferred to maintain a constant air temperature while allowing the gas volume to triple. calculate the required amount of heat transfer in kj/kg.