Two blocks are connected by a massless string that passes over a massless pulley
ID: 2172776 • Letter: T
Question
Two blocks are connected by a massless string that passes over a massless pulley. The block of
mass m1 sits initially on a flat frictionless surface, while the block of mass m2 hangs freely. When
the system is released, the masses move at constant acceleration.
a) Derive an expression for the magnitude of the acceleration using Newton
Explanation / Answer
The net force accelerating m2 is = m2*g - T (with T = tension) m2g - T = m2a --> T = m2g - m2a. And the tension is also the force that accelerates m1: T = m1a set both equations equal to get m2g - m2a = m1a --> solve for a: a(m1 + m2) = m2g a = m2g/(m1+m2) T = m1*m2*g/(m1+m2)