In: Physics
A 100g ball is tied to a string so that the center its mass hangs 60 cm below the point where the string is tied to a support rod. The ball is pulled aside to a 70° angle with vertical and released. As the string approaches vertical, it encounters a peg at a distance x below the support rod. The string then bends around the peg. If the position of the peg is low enough, the ball will move in a circle wrapping the string around the peg. a. Draw a FBD for the ball. Starting from the definition of work W=F d cos, demonstrate and explain the work done by each of the force on your FBD. b. What is the work done by nonconservative force? What can you say about the total mechanical energy for the ball as it swing and rotate around the support rod and peg. c. What is the smallest value of x for which the ball will move in a circle wrapping the string around the peg? Note: to answer the last question c, first explain what happen to the mechanical energy, gravitational potential energy, kinetic energy, speed, and centripetal force of the ball as you decrease x. Then predict what will happen to the mechanical energy, gravitational potential energy, kinetic energy, speed, and centripetal force when x reaches its minimum value. Set up a mathematical equation that satisfy the condition for minimum x and solve it based on the conditions provided.
the following answers have been solved as sub-question a. b. and c. and the solution is posted in the form of handwritten formate because it needs more diagrammatic support which is not possible with any writing software. so I m posting this written solution.
Answer a. Diagram or the schematic full body diagram.
Answer b. workdone by the conservative force.
Answer c. finding the smallest value of x for which the circular motion at peg is possible.