Final Answer:
a. The work done in raising the engine is 3500 kJ. b. The useful work done is also 3500 kJ. c. The efficiency of the chain and block pulley is 100%.
Step-by-step explanation:
In lifting the 875 kg engine with a chain and block pulley, the work done is calculated by multiplying the force applied, which is 5.0 x 10^4 N, by the vertical distance the engine is raised, which is 4.0 m. This results in a total work done of 200 kJ.
The useful work done against gravity is equal to the force applied multiplied by the distance lifted, yielding another 200 kJ. Notably, the efficiency of the chain and block pulley system is determined by the ratio of useful work to total work input. In this scenario, the efficiency is found to be 100%, indicating a highly effective system where all the input energy is utilized to overcome gravitational forces and lift the engine.
This ideal efficiency suggests an absence of energy losses within the system, showcasing the mechanical efficiency and effectiveness of the chain and block pulley mechanism. The 100% efficiency implies that the entire input work is converted into useful work, making this lifting process highly optimized and demonstrating the mechanical advantage of employing a chain and block pulley for such tasks.