In an Atwood machine (see Problem 3.30), the two masses are 800 g and 700 g. The

Question:

In an Atwood machine (see Problem 3.30), the two masses are 800 g and 700 g. The system is released from rest. How fast is the 800- g mass moving after it has fallen 120 cm?

Problem 3.30

A cord passing over a light frictionless pulley has a 7.0-kg mass hanging from one end and a 9.0-kg mass hanging from the other, as seen in Fig. 3-20. (This arrangement is called Atwood’s machine.) Find the acceleration of the masses and the tension in the cord. A 7.0 kg B 9.0 kg Fr A 7.0 kg Fig. 3-20 + FT B 9.0 kg (7.0 kg) g (9.0 kg) g Free-body diagram (b)