A grinning oddball of mass m stands a distance d from the bottom of a stationary ladder having mass M and length L, as in the figure. What is the magnitude of the friction force that the floor exerts on the ladder? Assume the wall is frictionless and 58 kg, M = 22 kg, L = 3.1 m, let m d = 1.3 m, and D = 1.2 m. d L m M ·D→ fs = N

12.3

Determine the equivalent force-couple system at the center O for each of the three cases of forces (F = 340 N) being applied along the edges of a square plate of side d = 230 mm. The couple is positive if counterclockwise, negative if clockwise. y y F d F -d- F Answers: (a) R=( i i+ i j) N, Mo = i N-m (b) R= ( i i+ j) N, Мо- N-m (c) R= ( i i+ j) N, Mo = N-m

Consider a horizontal forearm. On one end of the forearm is the elbow, and on the other end is the hand. The forearm has a mass of 5.00 kg. The distance from the elbow to the hand is 34 cm. If the biceps muscle connects to the forearm a distance of 5.50  cm from the elbow, and the biceps muscle can supply a maximum force of 775. N (with the forearm in a horizontal position), what is the maximum mass (in kg) that the person can hold? (What equation can I use to solve this problem? Shouls I assume that the center of mass of the forearm to be midway/ in the middle between the elbow and the hand?)