A light rope passing over a frictionless pulley connects two objects. One object has a mass of 10kg. The tension in the rope is 90N. Calculate the acceleration and the mass of the second object.

Question

Object 1
Fg-Ft = ma
100 - 90 - 10*a
10/10 = a
a = 1m/s^2

Object 2
Ft-Fg = ma
90-m10 = ma

I don't know what to do next. Help?

Answer 1

I believe you are using 10.0 m/s^2 for g.
Based on that, the acceleration is OK.

The accleration is the same for both objects. So put the value you found for acceleration into your calculations for Object 2. Now you have just an equation with m as the only unknown.