Lecture Week 9 Questions PDF

## F8-8 If the coefficient of static friction at all contacting surfaces is $μ_s$, determine the inclination $θ$ at which the identical blocks, each of weight W, begin to slide. The image shows two identical blocks, A and B, stacked on top of each other and lying on a ramp. Block A is on top of bl...

## F8-8 If the coefficient of static friction at all contacting surfaces is $μ_s$, determine the inclination $θ$ at which the identical blocks, each of weight W, begin to slide. The image shows two identical blocks, A and B, stacked on top of each other and lying on a ramp. Block A is on top of block B, and block B is on the ramp. The ramp is inclined at an angle $θ$ with respect to the horizontal. The blocks are connected by a system of pulleys, and the weight of each block is W. The coefficient of static friction between the blocks and the ramp is $μ_s$. ## Example 8.4 Beam AB is subjected to a uniform load of 200 N/m and is supported at B by post BC. The coefficients of static friction at B and C are $μ_B$ = 0.2 and $μ_C$ = 0.5. Determine the force P needed to pull the post out from under the beam. Neglect the weight of the members and the thickness of the beam. The image shows a beam AB supported at B by a post BC. The beam is subjected to a uniform load of 200 N/m. A force P is applied to the post BC, and the coefficients of static friction at B and C are $μ_B$ = 0.2 and $μ_C$ = 0.5. ## The uniform 10-kg ladder The uniform 10-kg ladder in Fig. 8-9a rests against the smooth wall at B, and the end A rests on the rough horizontal plane for which the coefficient of static friction is $μ_s$ = 0.3. Determine the angle of inclination $θ$ of the ladder and the normal reaction at B if the ladder is on the verge of slipping. The image shows a ladder leaning against a smooth wall at B, with its other end A resting on a rough horizontal plane. The ladder is 4 meters long, and the coefficient of static friction between the ladder and the plane is $μ_s$ = 0.3. ## Example 8.2 It is observed that when the bed of the dump truck is raised to an angle of $θ$ = 25°, the vending machines will begin to slide off the bed. Determine the static coefficient of friction between a vending machine and the surface of the truckbed. The image shows a dump truck with its bed raised at an angle of $θ$ = 25°. A vending machine is resting on the bed of the truck. The vending machine is about to slide off the bed of the truck. ## The uniform crate The uniform crate shown in Fig. 8-7a has a mass of 20 kg. If a force P = 80 N is applied to the crate, determine if it remains in equilibrium. The coefficient of static friction is $μ_s$ = 0.3. The image shows a crate with a mass of 20 kg, resting on a horizontal surface. A force P = 80 N is applied to the crate at an angle of 30° with respect to the horizontal. The coefficient of static friction between the crate and the surface is $μ_s$ = 0.3.