Consider the Atwood machine of the previous problem. The larger mass is stopped for a moment 2.0 s after the system is set into motion. Find the time elapsed before the string is tight again.
mass=m1 =300g, mass=m2=600g.
When masses m1 and m2 are connected by a string passing over a pulley and when the pulley comes in motion, then mass m2 is stopped in 2 seconds. So, equation of motion is:
T – m1 g = m1 a−−−−(1)
m2 g − T = m2 a−−−−(2)
On solving equations (1) and (2), we get,
a = 
=
= 
ms-2
In 2 second the velocity acquired by mass m1 is given by,
Applying first equation of motion,
0 = v −
×2 or v =
ms-1
with acceleration due to gravity i. e.
0 = −
− 10 t or t = 
= 
sec
1