Here is a chance to practice calculating accelerations on an Atwood machine and the tensions in the ropes. When you accelerate upwards against gravity you feel heavier. Your effective “g” is 9.8 plus your acceleration upwards. When you accelerate downwards you feel lighter. Your effective “g” is 9.8 minus your acceleration. Thus when you calculate w = mg, you use w = m (g effective) to find the tensions in the ropes. If you like this worksheet try "Forces on an Inclined Plane" also by Scorton Creek.