Final answer:
Lubricant reduces friction, improves machine efficiency, prevents wear and tear, and reduces heat generated due to friction.
Step-by-step explanation:
Lubricant affects the efficiency and frictional forces of a machine in several ways. Firstly, lubricant reduces friction between the moving parts of a machine by creating a thin layer that separates the surfaces in contact. This reduces the amount of force needed to overcome friction, leading to higher efficiency. Secondly, lubricant helps to minimize wear and tear on the machine's components by reducing friction, which can prolong the machine's lifespan. Lastly, lubricant can also increase the performance of a machine by reducing heat generated due to friction, preventing overheating and improving overall efficiency.