Katherine is attempting a biceps curl with a 10 kg dumbbell. She is standing upright, and her forearm is horizontal. The moment arm of the dumbbell about Katherine's elbow joint is 25 cm.

1. What is the torque created by the dumbbell about the elbow joint?

1. If the elbow flexor muscles contract with a force of 500 N and hold the dumbbell in static equilibrium, what is the moment arm of the elbow flexor muscles about the elbow?

1. If Katherine holds the dumbbell with her arm by her side (i.e. her arm is straight and pointing downward), what is the torque created by the dumbbell about the elbow joint (assume that in this position the dumbbell is in line with the elbow)?