A single movable Lully is being used to move a 140 N load. The pulley is a little dirty, so it adds another 5 N frictional force. Would a single fixed pulley work? explain your answer.
No, a single fixed pulley would not work in this situation.
A fixed pulley changes the direction of the force applied, but it does not provide any mechanical advantage in terms of reducing the amount of force needed to lift a load. In this case, the load is 140 N and with the additional 5 N of friction from the dirty pulley, a total force of 145 N is needed to move the load.
Using a single fixed pulley would not reduce the amount of force needed to move the load, so it would not be effective in this scenario. A movable pulley, on the other hand, allows for a mechanical advantage by distributing the force needed between the pulley and the user, making it easier to move the load.