Talk:Seddie/@comment-4336877-20140211122749/@comment-14284535-20140214020752

Check out these boards? Can you imagine having a problem like this.

Carly, Sam, and Freddie are duct-taped to three plastic chairs, each of which is 5kg. Carly and Sam weigh 45kg and Freddie weighs 50kg. They are each 1.5m tall.

The ratio of the vertical heights of the foot & shin : thigh : trunk : neck & head is 29 : 24 : 30 : 11.

The ratio of the masses of the same segments is 6 : 15 : 47 : 7.

The seat of the chair is 15% of its mass; the backing and backing frame of the chair is 25% of its mass; and the base frame of the chair is 60% of its mass.

The base frame of the chair is .5m high; the seat of the chair is .5m long, and the backing of the chair is also .5m high.

For simplicity: assume that they are seated with their head, neck, backs, and shins being perfectly vertical while their thighs and feet are perfectly horizontal; assume the the weights of each part of their bodies is uniformly distributed through that part of the body; and assume the weights for the different parts of the chair are uniformly distributed through each segment as well.

Using this information, compute the minimum torque required to cause them to fall over backwards. (Hint: use the back base of the chair as the origin of your reference frame.)