Two blocks of masses 2 kg and 5 kg are at rest on ground. The masses are connected by a string passing over a frictionless pulley which is under the influence of a constant upward force F = 50 N. Find the accelerations of 5 kg and 2 kg masses.

Two blocks of masses 2 kg and 5 kg are at rest on ground. The masses a

1.	Two blocks of masses 2 kg and 5 kg are at rest on ground. The masses are connected by a string passing over a frictionless pulley which is under the influence of a constant upward force F = 50 N. Find the accelerations of 5 kg and 2 kg masses.
Answer» SOLUTION :The masses will be lifted if the tension in the string is greater than the gravitational pull on masses. Weight of 5 kg mass `= 5xx10 = 50 N` and that of 2 kg mass `= 2xx10=20 N`. From free BODY diagram `50-2T = 0` or T = 25 N (`because` pulley is massless) Tension in each string = 25 N. 2 kg weight will be lifted. But 5 kg weight can not be lifted ACCELERATION of 2 kg weight : `rArr 25-20 = 2a`or `a=(5)/(2)=2.5 ms^(-2)` as the 5kg mass does not lifted, so its acceleration is zero.