3 - A box of mass 2 Kg lies on a rough horizontal floor with the coefficient of friction between the floor and the box being 0.5 (Figure 3). A light string is attached to the box in order to pull the box across the floor. If the tension in the string is TN, find the value that T must exceed for motion to occur if the string is 30º above the horizontal.

Question

Figure 3

Answer 1

Determine the distance to which the 90 kg painter can climb without causing the 4 m ladder to slip at its lower end A as shown in Figure 1. The top of the 15 kg ladder has a smaller roller, and at the ground the coefficient of static friction is 0.25. The mass center of the painter is directly above his feet.

Figure 1

Answer 2

232